Introduction

One of the objectives of the United Nations 2030 agenda is assessed by the Sustainable Development Goal (SDG) 16.4: Significantly reduce illicit financial and arms flows, strengthen the recovery and return of stolen assets and combat all forms of organised crime (United Nations, 2023). In this respect, the illegal drug trade represents a significant challenge for societies worldwide, driving complementary crimes and socio-economic disruptions. Illegal drug trade encompasses various activities, such as cultivation, manufacturing, distribution, and sale of prohibited substances, with specific legislation varying across countries (Caulkins and Reuter, 2006; Draca et al. 2019; United Nations Office on Drugs and Crime, UNODC, 2022) and links with numerous crimes (DCSA, 2023).

Quantifying the volume of drugs produced and traded is a complex challenge, with illegal drugs accounting for approximately 20% of criminal activities and fluctuating between 0.6–0.9% of the world’s GDP (UNODC, 2016). The European drug trade is estimated to be worth EUR 31 billion, with drug cartels involved in increasing complexity encompassing various substances (EMCDDA, 2024), also involving online trading, especially during and after the COVID-19 lockdowns (Blankers et al. 2021; Palamar et al. 2021; EMCDDA, 2022; Andrei et al. 2023).

Rising unemployment rates, limited education and employment prospects, and stagnating minimum wages incentivise involvement in unlawful activities such as drug production and trade (Coughlin and Venkatesh, 2003; Cramer, 2010; Nelson, 2024). As Andell et al. (2023) show for the United Kingdom, a vulnerability in youth often leads to the exploitation of street gangs by organised criminal groups in drug smuggling. Despite illegal drug seizures being a commonly analysed indicator, quantitative data on this hidden activity are scarce (Beckert and Wehinger, 2013; Moeller et al. 2021; Raineri and Strazzari, 2023). Additionally, less research is dedicated to combining illegal drug seizures with prices to compute potential revenues and evaluate the economic impact (Moeller et al. 2021) and possible specialisations at a country level.

Being such a complex phenomenon, research on illegal drugs should include more diverse data, sources, and complementary methods (Sánchez-Pérez et al. 2023). Addressing this research gap and aligning with UN SDG 16.4, this paper introduces a novel integrative method analysis focusing on the supply side, shedding light on the transformations in criminal activities and society resulting from international drug trade and organised crime groups (OCG) infiltration. The peripheral region of Sardinia (Italy) offers an interesting setting for examining the evolving criminal structure, marked by new, more profitable, less prosecutorial risky forms and new criminal ties (Becker, 1968; Marongiu and Clarke, 2004; Detotto et al. 2015; Villani et al. 2019; Mirenda et al. 2022; DIA, 2022).

The annual report by the DCSA (2005) remarks that the Calabrian ’Ndrangheta, in Italy, adapted its strategies to retain control over the lucrative drug trade, amid growing interest from national and foreign criminal groups. These activities led to ever more novel alliances with like-minded national and international OCG, expanding their influence beyond their traditional regional boundaries. Over time, this mafia has acquired a preeminent role in the transnational drug trade, money laundering, and infiltration in the legal markets position, and can acquire trust from South American producer cartels and especially from the Mexican cartels (DCSA, 2014; DCSA, 2023; Sergi, 2023).

These complex and fluid activities require multifaced quantitative and qualitative approaches to explore trends, dynamics, and future projections of OCG. On the one hand, quantitative data (e.g., quantity seized, prices, potential revenues) and probabilistic analysis can first glance at comparative cross-countries advantages, specialisations and main drivers of OCG. On the other hand, the 'collective’ narrative, relevant within a socio-economic context, provides richer microeconomic information on complex agents’ behaviours and implications for policymakers (Roos and Reccius, 2024).

The present research analyses a subset of Court judgements (1997–2018) on breaching Italian Presidential Decree 309/90: Art. 73, unlawful production and trafficking of narcotics or psychotropic substances; Art. 74, an association formed with the specific purpose of engaging in the illicit trafficking of such narcotics or psychotropic substances (Gazzetta Ufficiale, 1990). Specifically, the focus of the paper is founded on illegal national and international drug trade, having the Italian region of Sardinia as a novel barycentre (DIA, 2022). Computer Assisted Qualitative Document Analysis Software (CAQDAS) is a common tool adopted in social sciences, although only very recently applied to heterodox economics (Prabowo, 2020; Oleinik, 2022; Roos and Reccius, 2024; Nelson, 2024). Content analysis on legal documents unveils other faces of criminal activities and their interconnections that quantitative data cannot address comprehensively (Schebesta, 2018). This approach also expands the understanding of agents’ behaviour, production process, complementary and substitution effects, specialisation, and policymaking effectiveness as typical objectives of economic theory (Roos and Reccius, 2024).

Literature review

Illegal drugs and complementary crimes

In the EU, during the two-thousands, there has been a shift towards domestic cannabis and a surge in its cultivation, especially in the Mediterranean area, associated with the illegal drug trade (Alvarez et al. 2016). The cultivation of cannabis for illegal trade changes the use of territories and is an essential source of income for producers and drug dealers, enhancing OCG ties. Indeed, the literature defines the drug business as the most significant illegal economic activity globally and in many individual countries (EMCDDA, 2024). Yet, the estimation of its actual size is challenging since official data cannot easily trace these economic activities (Reuter and Greenfield, 2001; Kilmer and Liccardo Pacula, 2009; Khaled, 2013; Vopravil and Rossi, 2013; Caulkins and Reuter, 2022; Udrisard et al. 2022; Raineri and Strazzari, 2023), although policymakers need precise data to assess the costs, evolution and future projections (Babor et al. 2018; Kilmer et al. 2014).

The study of illegal drugs has been dominated by quantitative approaches (Espinosa, 2019; Mclean et al. 2019; Moeller et al. 2021). Detotto and Vannini (2010) estimate that in Italy, the social burden of drug dealing accounts for the highest cost of all crimes analysed (more than 7 billion euros), mainly due to health services and drug-related deaths. Besides, this unlawful activity may hide competition amongst growers and distributors, and commodity chain structures are often characterised by violence that adds extra material and immaterial costs (Cocklin et al. 1999; Mejía and Restrepo, 2016), jointly with extra costs of eradication policies (Mejia and Restrepo, 2016).

The literature distinguishes between two methods for estimating the size of illegal drugs business, a supply-side approach and a demand-side approach, although one method is not regarded as better than the other (Kilmer et al. 2014; EMCDDA, 2019; Parey and Rasul, 2021). Sánchez-Pérez et al. (2023), for example, analyse the hashish (also named as cannabis resin) supply chain from Morocco to Europe, employing integrative methods based on primary data gathered from interviews administered to cannabis producers and dealers and secondary information retrieved from official statistics, research papers, informational reports, and documentaries. The authors unveil unequal distributions and a 7000% increase in end-user prices from production costs.

In recent years, the surge in illegal drugs also using the dark web, especially during the COVID-19 pandemic, raised further complexity in tracing sales and consumption in these hidden markets and further complicated estimating its actual size. Moreover, evidence suggests that dark web users prefer to operate online to avoid the violence generally associated with the street drug trade (Kruithof et al. 2016; UNODC, 2020; Chawki, 2022). Munksgaard and Tzanetakis (2022) analyse drug pricing formation through a multilevel linear regression on prices in two crypto markets. The findings reveal payment method price adjustment but no evidence of the impact of reputation and status. Besides, online markets tend to mirror external institutional constraints and social processes.

Research also attempts to identify complementary crimes of illegal drugs. Organised crime groups devoted to the drug business tend to diversify their trade portfolio in other illegal activities to maximise profits. Detotto and Pulina (2013), employing a Vector Error Correction Mechanism (1981q1–2004q4, for Italy), unveil a complementary effect between serious crimes (e.g., robberies, extortions, kidnapping) and relatively less severe crimes, such as drug-related crimes. Hughes et al. (2020) show that, in Australia, the drug trade overlaps with weapons and illegal commodities trafficking and leads to corruption, bribery, and money laundering. For Italy, Daniele and Dipoppa (2022) assess a link between mafia infiltrations and legal firms that exhibit lower performance, project delays, and suspicious timing in public subsidy applications. Lower bank debt aligns with money laundering practices of mafia-infiltrated enterprises. Through a difference-in-differences approach, Di Cataldo and Mastrorocco (2022) unveil mafia infiltrations within local governments, mainly active in the construction sector and waste management, especially in the South of Italy.

Organised crime groups diversify their trade portfolio in other illegal activities to maximise profits. Belhabib et al. (2020) explore the association between fisheries and drug trafficking worldwide (years 2010–2017) and reveal declining fish stocks in many areas, even in strict marine protected areas, because of increased competition and overinvestments in the sector. In the same line of research, Van Uhm et al. (2021) emphasise the importance of exploring the overlapping between drug business and environmental crimes in connection to the wildlife trade of rare species. Zambiasi (2022) analyses the impact of shutting down Dark Net marketplaces on street drug smuggling and related crimes. The study used a regression discontinuity design and found that closing these marketplaces led to a significant increase in street drug trading in the short run but had no impact on thefts, assaults, or homicides.

Content analysis by CAQDAS and legal documents

Recent studies have adopted qualitative methodologies to explore illegal drug markers (Aldridge and Décary-Hétu, 2016; Syvertsen et al. 2016; Bakken, 2020, Bakken and Demant, 2019; Van der Sanden et al. 2022; Nelson, 2024). Combining quantitative and qualitative research within a multidisciplinary perspective would enhance the understanding of agents’ complex and hidden behaviour. CAQDAS (e.g., ATLAS.ti, MAXQDA and Nvivo) are well-established tools for supporting qualitative research and eliciting technical information by combining machine automation with human analytical knowledge (Woods et al. 2016).

While CAQDAS supports working collaboratively, researchers need to be conscious that 'reflexive thinking' is necessary to develop awareness about its impact on research analysis (Brown, 2002) and to understand how it fits with their analysis approach and techniques (Woods et al. 2016). CAQDAS supports various qualitative methods and methodologies/frameworks (i.e., grounded theory, content analysis, and thematic analysis). These tools are useful for analysing texts from several sources, such as sample surveys and social media (Woods et al. 2016; Nelson, 2024), although they are less commonly used for legal documents (Dobinson and Johns, 2017; Hall and Steine, 2020; Salahudin et al. 2020). In the legal literature, content analysis is commonly used to identify the reasoning behind court verdicts (Mohamad, 2014; Brayman, 2016), and it can be automated to facilitate the interpretation of legal Supreme Court briefs and identify opposing positions on a debate (Evans et al. 2007). Content analysis can also investigate institutional variation across American Indian constitutional texts, revealing key political and socio-economic outcomes (Cordell et al. 2020). Hall and Wright (2008) suggest that content analysis allows legal scholars to present their analytical insights in a way that is taken seriously by the broader social science community.

Research questions

The present research contributes to this literature thread with a supply-side perspective and a more comprehensive understanding of trends, dynamics and future projections of complex agents’ behaviours through a mixed-method approach. Specifically, the following research questions are addressed.

  • RQ1: What kind of drug trade specialisation exists? This objective involves combining data on drug seizures and prices for different illegal drugs. It examines specialisation at both the European and Italian regional levels.

  • RQ2: Are there complementary effects between drug trade and other crimes? This objective is explored through content analysis and a probabilistic model with matrix data collected on the legal judgements and analysed through CAQDAS and econometric software.

  • RQ3: Is there a discernible relationship between drug-related crimes and organised crime in a peripheral region? This research question explores the interconnectedness between drug-related offences and organised crime within a peripheral region. This objective is assessed through the content analysis and the probabilistic modelling.

By addressing these research questions, the study provides valuable insights into the multi-faceted nature of the illegal drug trade and its implications for criminal activities and societal structures, within a peripheral region such as Sardinia such as the Italian region of Sardinia (Licio and Pinna, 2021; Blečić et al. 2023).

Integrative methodology

Quantitative tools

A quantitative analysis is used further to interpret qualitative research on the most consumed illegal drugs and identify possible specialisations (RQ1). A supply-side approach is adopted to estimate the economic size using official drug seizure data (Parey and Rasul, 2021).

The economic value of quantities seized is analysed at the EU level, and a regional analysis is conducted for Italian regions. Quantities seized and prices per gram or dose are extracted from the European Monitoring Centre for Drugs and Drug Addiction. The panel matrix has a time dimension t and an individual dimension for EU country i, (and Italian region i), which contains the quantity seized q, and the maximum and minimum price. Based on the average price (p), we calculated the potential revenue (RT) of the seized quantity over a population of, respectively, one million inhabitants for the EU countries and 100,000 inhabitants for the Italian regions, for a homogeneous comparison between countries/regions. The generic formula used for the calculation is as follows:

$${{\rm{RT}}}_{{\rm{i}},{\rm{t}}}={{\rm{p}}}_{{\rm{i}},{\rm{t}}}* {{\rm{q}}}_{{\rm{i}},{\rm{t}}}$$
(1)

This specification addresses possible drug specialisations at the EU and regional levels, respectively (RQ1), providing an overview of the phenomenon (Baika and Campana, 2020).

As stated, the quantitative approach based on official statistics presents shortcomings, as it cannot rely on a systematic basis for estimating the actual seizure rate (Kilmer et al. 2011; Nelson, 2024), especially in the underground economy.

Qualitative method

The qualitative method has been employed only recently in the economics literature, although it offers a wide range of investigations based on sound theoretical frameworks. Indeed, the economic analysis is grounded in agents’ behaviour and is considered complex and uncertain (Oleinik, 2022). This complexity necessitates a more holistic understanding through complementary and interdisciplinary approaches to the standard indicators retrieved from statistical institutions, ad hoc structured surveys or experimental settings.

In this context, Roos and Reccius (2024) identify three main paradigms based on textual 'collective' narrative: as a driver of the economy (at micro, meso, and macro levels); as a medium for policy analysis (fiscal and monetary policies), and, more generally, within the welfare state policymaking; and as an interpretative summary of information/data. In this respect, content analysis offers a robust approach to exploring OCG as a complex system characterised by interpersonal and intergroup ties in continuous motion, constantly revitalising and reinforcing itself (Arthur, 2015). By employing content analysis, this study anchors to these paradigms within an interdisciplinary perspective to provide a more comprehensive understanding of the socioeconomic implications of OCG’s behaviour in terms of dynamics and complementary crimes.

The content of the legal judgements was analysed using systematic, rule-guided techniques through ATLAS.ti 7.5 software (Worthington and Whittaker, 2006; Bussu et al. 2023; Bussu, 2016). The codification was done on three levels (i.e., open code, axial coding, and selective coding) to define the core category of the primary documents in the hermeneutic unit (HU). The interdisciplinary perspective is guaranteed by the interactions among four researchers with different specialisations (i.e. economics, forensic psychology, legal and sociology) who analysed the data. The whole research team provided continuous feedback.

The first coding approach to the legal judgements’ main body is general. The second approach involves simultaneous coding when the offender committed multiple crimes in different places and/or other times of the same day (e.g., drug business, organisation, logistics, money laundry, racket) (Schebesta, 2018).

Codes were obtained from the conceptual literature, and new keywords and themes emerged from the punctual text coding through the HU (Saldaña, 2016; Dalla Chiesa and Dekker, 2019). Hence, as a synthesis, Primary Document Families were identified, expressing a given construct or semantic concept (Franzosi et al. 2013; Friese, 2014).

The analysis followed Patton’s (2002) criteria and the quality criteria guidelines proposed by Seale (1999) (i.e., credibility, transferability, dependability, authenticity, confirmability), further validated through an iterative and progressive interpretive process using triangulation from different sources and methods (Johnson, 1997; Golafshani, 2003; Greene, 2006). Quotations addressed informative content about criminal actions, complementary crime activities, and interrelationships between local and specific national/international criminal organisations that help address RQ2 and RQ3.

The probabilistic framework

A qualitative analysis provides informative data that can also be converted into a matrix of quantitative data that, in the second stage, can be analysed using parametric specifications, such as probabilistic methods (Lewis, 2016; Smith, 2021). Qualitative information is converted into a quantitative data matrix to better understand the role and interconnections of organised crime groups. This allows for applying a probabilistic logit model, which is well-suited for scenarios where the dependent variable is binary (Hill et al. 2018). The generic logit model is specified as follows:

$${\rm{Logit}}({\rm{P}}({\rm{Y}}=1))\,={{\rm{\beta }}}_{0}+{{\rm{\beta }}}_{1}{{\rm{X}}}_{1}+\cdots \cdots +{{\rm{\beta }}}_{{\rm{k}}}{{\rm{X}}}_{{\rm{k}}}$$
(2)

where P(Y = 1) is the probability that the event occurs, while Y = 0 is the probability that the event does not occur. β0 is the intercept, and β1 ….. βk are the parameters of the explanatory variables X1……Xk to be estimated. A specific-to-general approach involves testing a series of nested models to ensure that the final model is both parsimonious and comprehensive and that the overall goodness of fit holds.

Hence, this logistic specification estimates the likelihood of an organised crime group’s involvement in various activities and understands the key drivers that differentiate organised and non-organised crime groups, according to the Law definition. This probabilistic approach provides valuable insights into the structure and dynamics of organised crime, addressing RQ2 and RQ3.

The case study and the sample

The Italian legal system regulates the possession of illegal drugs through the Presidential Decree (No. 309, 9th October 1990), which includes Art. 73, which covers various drug-related offences such as cultivation, transfer, production, extraction, and refining (Paragraph 1). Various paragraphs of Art. 73 further regulate the penalties for these offences that vary depending on the type of drugs (‘not minor quantity’; cocaine and heroin as ‘hard drugs’; cannabis resin and herbal cannabis (namely marijuana) as ‘soft’ drugs; Paragraphs 1, 1a); severity of the actions and conduct (Paragraph 4, and 5); and increase if the activities are carried out by three or more persons (Paragraph 6). Hence, in Italian legislation, criminal organisations are intended as a form of associated delinquency that presupposes a stable organisation of multiple individuals (more than two) for drug trade and associated with various crimes for financial or material gain (Art. 74). In Italy, this phenomenon is mainly associated with highly structured criminal groups such as the Sicilian mafia, Camorra, Sacra Corona Unita, and especially Calabrian ‘Ndrangheta that is the leader in the international narco-trade (Calderoni, 2012; DCSA, 2023). Organised crime has become a separate entity that operates as a significant criminal power competing within the legal system and is present in various sectors of society, including political parties, local administrations, and public institutions (DIA, 2022).

The present study’s primary sources consisted of legal documents from the Court of Cagliari (Sardinia, Italy) from 1997 to 2018, made available to the Social Observatory on Crime in Sardinia (OSCRIM). For privacy compliance, all documents were used anonymously with written permission from the Court of Cagliari. The aim is to detect changes in the regional socio-economic structure that only recently became the new pivotal centre of the national and international drug trade as addressed by the Italian Ministry of Home Affairs (DIA, 2017; DIA, 2022). The initial screening focused on 634 collegiate Court sentences, from which only those related to illegal national and international drug trade were selected, according to Presidential Decree 309/90 (Art. 13 and Art. 14). A total of 45 sentences were chosen after further selection procedures. Acquittals were excluded from the sample. Two sentences reported identical charges concerning two defendants; relevant information was merged into one document. At the end of this final selection process, only 36 were considered eligible. The length of these judgements varied from a few pages to over 400 pages of reasoning, for a total of 1145 pages codified by the research team.

An overview of illegal drug specialisation in Europe

This section provides an overview of drug ‘specialisation’ among EU countries. The comparison includes Austria, Belgium, France, Greece, Hungary, Italy, Latvia, Poland, Romania, and Sweden, from 2011–2019, given the data availability. Notably, cocaine prices increased over time, while heroin prices decreased from 65.1 euros per gram in 2011 to 57.7 euros per gram in 2019. Cannabis resin prices were slightly reduced, while cannabis leaves saw an increase in average price. Amphetamines and MDMA (dose) prices increased over time (see left-hand side Figure A.1, Appendix A). On the right-hand side, drug seizures are displayed, with cocaine seizures showing the highest increase (+201.7%), followed by cannabis leaves (+138%), amphetamines (+52%), and cannabis resin (+43%). MDMA saw a relatively minor increase in seizures (+10.5%). The rise in drug seizures post-economic crisis could be due to various factors. This outcome could be driven by the standard law of supply and the positive price-quantity correlation. However, this effect is not recorded for heroin that, despite a reduction in the average price, experiences a significant increase in seizures. A second factor could be attributed to the law of demand; in equilibrium, a demand increase drives increased prices and quantities traded. A further element could be due to law enforcement and intelligence operations at a European driving more systematic seizures.

Figure 1 provides the quotas of potential revenues from drug seizures between 2011 and 2019 for a selected group of European countries. For a homogenous comparison, the revenues are normalised by 1 million inhabitants (source: www.ggdc.net/pwt).

Fig. 1: Quotas (%) of potential revenues by drug type and country (2011–2019).
figure 1

Notes: Own elaboration on EMCDDA for prices and quantities.

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Belgium has the highest share of potential revenues from seizures for cocaine (86.0% of the total) and heroin (26.9%). Sweden has a relatively high seizure rate for amphetamines (64.0%), while Austria has the highest percentage for doses of MDMA (25.2%). Italy has the highest share of potential revenues for cannabis resin (33.2%), followed by France with 24.9%, and Greece stands out for the highest share of the economic value of illegal herbal cannabis (57.0%).

An overview of drug specialisation in Italy

According to ISTAT (2022), in 2020, household expenditure for illegal drugs in Italy was estimated at euro 14.8 billion, and the value added was euro 13.3 billion. Figure 2 displays the quotas of potential revenue estimates of cocaine, heroin, hashish, and marijuana seizures in Italian regions (averaged from 2008–2019 per 100 thousand inhabitants). Calabria and Liguria show the highest cocaine shares of 38.0 and 28.4%, respectively. Liguria, with its harbour of Genova, also leads in heroin (20.2%) and hashish seizures (18.0%). Sicily ranks first for hashish seizures, with a share of 30.4%, while Sardinia ranks third with a share of 16.7% of the total. As regards the trade of marijuana, Puglia dominates the national panorama with an average percentage of 35.3%.

Fig. 2: Quotas (%) of potential revenues by drug type and region (2011–2019).
figure 2

Notes: Own elaboration on EMCDDA for prices and quantities.

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Although based on seizures, these results in the EU and Italian regions mirror a degree of specialisation at a territorial level (RQ1). In this regard, the present research provides further evidence of forms of specialisation in illegal drugs. For example, Baika and Campana (2020) find a high degree of specialisation amongst suppliers and types of drugs in the UK. Heroin and cocaine present relatively low levels of fragmentation because the trade requires high-profile network cooperation (see also Bajri, 2015). These findings also align with those by Alvarez et al. (2016), who detected a shift towards domestic cannabis cultivation in the Mediterranean areas during the 2000s associated with illegal drug business.

A brief account of the evolution of crime in Sardinia

In 1969, the Italian Parliament appointed an ad hoc commission to investigate crime in Sardinia, which concluded that crime was deeply rooted in the rural world centred in Barbagia and neighbouring districts (Medici, 1972). While recent studies have shown a weakening of this ‘rural dimension’ of crime, crime in Sardinia has evolved into new forms, including the cultivation of cannabis and drug trade, with changes in the type of offences and level of organisation involved (Marongiu and Clarke, 2004; Mazzette, 2014; Detotto et al. 2014, 2015; Direzione Nazionale Antimafia e Antiterrorismo, 2017; Villani et al. 2019).

Over time, Sardinian criminal groups have abandoned the practice of kidnapping for extortion, redirecting their interests towards more lucrative criminal activities, such as drug cultivation and trade. They have also formed connections with mafia organisations engaged in money laundering, particularly in the services sector, such as commerce and hospitality, which is pivotal for the Sardinian economy (DIA, 2018, 2022; CRENoS, 2024).

This Mediterranean Island is considered a European peripheral region due to its insularity, remoteness from the mainland, and declining population, leading to increased socioeconomic vulnerability (Licio and Pinna, 2021; Blečić et al. 2023). In the last decade, Sardinia has also experienced a deep economic crisis like other regions in Southern Italy, with high levels of unemployment, particularly among young people, and a low ranking in key indicators for human capital formation and accumulation, increasing socio-economic distress and vulnerability (CRENoS, 2024).

For the first time in 2016, the police operation Lex documented how members of the ‘Ndrangheta were connected to autochthonous OCG in Sardinia within supply routes originating from India and Colombia, converging at the port of Gioia Tauro in Calabria (DIA, 2016; DIA, 2017). Since then, Sardinia has progressively become a pivotal international hub for illegal drug trade (Direzione Nazionale Antimafia e Antiterrorismo, 2017; DIA, 2022). Furthermore, the forms of crime, in terms of offences, organisational structures, locations, and interactions with national and international OCGs, the legal economy, and public institutions, have undergone significant changes (DIA, 2022).

Findings

Dimensions, families, and indicators

To understand the complex interconnections between organised crime and the drug business, a broader perspective is required (Bajri, 2015; Baika and Campana, 2020). Qualitative analysis of legal judgements on 11 families and 120 macro codes uncovers multi-faceted elements of the drug trade (Yin, 1994). As shown in Table 1, the first dimension (who) includes information about the defendant’s profile and status and the victim’s information. The second dimension (what) includes various families, such as illegal drug specialisations, complementary crimes, penal code imputation, judgement outcomes, types of drugs and weapons involved. The third dimension (where) includes the place of the crime and the drug itinerary. The fourth dimension (when) consists of the year, month, day, and time of day (Table 1). By analysing these dimensions, one has a deeper understanding of the evolution of organised crime groups and drug business, including knowledge, skills, mutual trust, and sources of resilience (Villani et al. 2019). In the third column of Table 1, the ‘macro-codes frequencies’ denote how often broader thematic codes are applied to data, summarising or aggregating specific codes. These frequencies illuminate the prevalence of key themes or categories, facilitating the identification of significant trends within the analysed content, in line with a content analysis approach (Ashton and Bussu, 2023).

Table 1 Dimensions, families, and indicators.
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Illegal drugs and complementary crimes

A network depicts the interactions between illegal activities and crimes (Fig. 3) based on the families identified in the previous section. This network provides a comprehensive representation of the coding carried out in this study, using legal judgements and criminal charges. The network highlights the most relevant codes that emerged from the data analysis performed by ATLAS.ti, and the relationships among them.

Fig. 3: Illegal activities.
figure 3

Illegal activities, drug business, and crime interactions.

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In the network, each code includes two numbers: the first represents the frequency of a given code within the primary documents provided in the Hermeneutic Unit (HU). The second number refers to the direct associations with other codes.

The core dimension of the network is ‘Illegal activities’, which describes the interaction among 30 macro/codes. As presented in Table 1, from the content’s relevance and interactions among the codes, four main sub-dimensions emerge considering the above-mentioned families and the macro-codes significance: drug trade; logistic and crime operations; local drug dealing; weapons: guns and explosives.

Drug business

In the legal judgements analysed, the first sub-dimension of the ‘Drug trade’ refers to the consistent trade of illegal drugs, sometimes reporting specific quantities seized (e.g., several kilograms) and other times to not modest amounts. The potential revenues within an organised trade network often refer to several hundred thousand euros, then traded independently by other affiliates or individuals associated with local buyers.

The macro code drug trade (498 frequencies; 12 interactions) is further associated with several relevant codes: with several relevant codes: crime place South Sardinia (449; 3 interactions) as the pivotal centre of this research; place drug dealing: public area (55 frequencies; 1 interaction); itinerary: South Italy-Sardinia (54 frequencies; 1 interaction); organised crime (44 frequencies;1 interaction); cannabis cultivation (25 frequencies; 1 interaction); job status: public administration (12 frequencies; interaction 1).

These associations provide further insights into drug-related crimes and OCG in a peripheral region, highlighting all members’ skills, specialisations, and roles, including external collaborators not formally part of the criminal network (RQ3).

On different occasions, criminal organisations exploit local public officers to maximise their business and strategic interests, which poses a real threat to civil society. Infiltration of organised crime groups into the economic sectors and involvement in white-collar or corporate crime is also observed, as noted in other studies (Ruggiero, 2000; Benson and Simpson, 2014; Hataley, 2020; Sergi and Vannucci, 2023). This outcome highlights the risk of infiltration of local public administrations by criminal mafia groups as they continue to expand their criminal activities (DIA, 2022; RQ2).

Drug trade links to organised criminal networks involved in illegal activities across various Italian regions (especially Calabria and Campania) and other countries (e.g., Albania, China, Netherlands, Romania). Several illegal structures were detected, and several typical mafia criminal organisations were identified in Sardinia (Villani et al. 2019). As highlighted by Calderoni (2012), the formal hierarchy of mafia groups, especially ‘Ndrangheta, does not play a significant role in the drug business. However, members have a task division and status differentiation, with criminal leaders playing a crucial role.

Besides, the Court judgements often refer to minimal structures with leaders and participants characterised by task division. The promoter of the criminal association initiates illegal drug activity and contributes the most to the group or holds a supremacy and management role. The organiser coordinates illegal activities (e.g., trade, marketing, and retail), defines the rational use of infrastructures and resources, and finds necessary means for criminal actions. Participants support the pursuit of criminal association objectives.

For example, in one of the sentences analysed, the defendants established five operational groups, comprising Italians (located in Lombardy and Sicily) and foreigners (the Netherlands, Romania and Albania), linked to an international drug business organisation to acquire drugs, especially cocaine, from the group of suppliers and then trading in Sardinia through a dense system of drug dealers (RQ3). In another sentence, a Nigerian defendant created a single organisation with a triangulation between Sardinia, Campania, the Netherlands, and the UK, dedicated to import-export and transport of large quantities of heroin and cocaine to be sent to the local market in Cagliari. The Sardinian organised crime groups could travel to Venezuela and acquire the drugs destined for local criminal groups (RQ3). In another sentence, the criminal association acquired large quantities of cocaine, stored in Portugal and Spain, from parallel criminal organisations to import and trade in Italy. Regarding RQ3, the drug routes involved mainly the Southern Italian regions, especially Campania. This connection implies that the drug trade in Sardinia is to be framed in connivance with the Camorra, which tends to cooperate with the ʼNdrangheta that, as already said, is the leader in the international drug trade.

Villani et al. (2019) reported that several operations were conducted to reduce international drug business involving Sardinia and other national/international routes, dismantling two dangerous organised crime groups engaged in the drug trade. The first operation that involved Sardinia (‘Freccia Sarda’ -Sardinian arrow), DIA, 2017) identified an organised crime group of Nigerian and Italian criminals engaged in international drug trade between Sardinia, Campania, South America, and the Netherlands. A second operation (‘Il Principe e la scheda ballerina’-The Prince and the dancing card), see also Lindelauf et al. 2009) allowed for the arrest of several clan members belonging to the Camorra cartel of Casalesi operating in the sector of social and healthcare services in local districts. Drugs in Western Europe are traded through different routes. The Balkan route is one of the major pathways for the drug trade in all of Europe, passing through the eastern-central (Turkey-Bulgaria-Romania-Central Europe), southern (Turkey-Greece-Italy), and western (Macedonia-Albania; Macedonia-Kosovo/Serbia-Bosnia and Herzegovina; Bulgaria-Serbia and Bosnia and Herzegovina; and Croatia) regions. The drug routes are mostly related to the heroin and cocaine trade. In Italy, the leading suppliers are the various Italian mafia groups: Cosa Nostra (Sicily), Sacra Corona Unita (Puglia), and Camorra (Campania), which have started cooperating more and more with the ʼNdrangheta (Calabria), the pivotal player in the international drug trade (Gratteri, 2017). As a further generalisation and confirmation of these results, Fig. 3 shows that drug trade is a significant cause of connections with organised crime, as indicated by 44 frequencies and 1 interaction. Family networks also support this connection, as evidenced by 22 frequencies and 1 interaction.

Hence, to fully comprehend the drug business, it is essential to examine the social connections between countries, communities, and criminal groups operating in each territorial context, including macro, meso, and micro levels (Aziani et al. 2021; see also Roos and Reccius, 2024). Informal networks are a fundamental component of organised crime activities, and local and peripheral social interactions play a vital role in their consolidation, often based on friendship, family ties, background, ethnicity, language, and values (Lipsey and Derzon, 1998; Pratt and Cullen, 2005; Aziani et al. 2021). Social ties and community identity are crucial for strengthening criminal organisation networks (Buonanno and Pazzona, 2014). According to Kleemans (2012), there are five established mechanisms for involvement in criminal activity: social ties, work ties, deliberate recruitment, leisure activities, and life events (Madarie and Kruisbergen, 2020). Structured criminal organisations, such as mafia families, often work jointly with unstructured criminal groups (Reuter, 2009).

The analysis also reveals a correlation between the drug business and the economic crisis (2011–2017) (90 frequencies, 2 interactions), consistent with other field studies. For instance, Dom et al. (2016) note that the 2008/2009 economic crisis increased the number of people with problematic drug use in the European Union, particularly in certain countries (e.g., Greece, Cyprus, Ireland, Italy, Portugal, and Spain). Additionally, Italy has seen a rise in the consumption of cheaper drugs like marijuana and amphetamine and illegal cannabis production, especially in socio-economically disadvantaged areas where legal job opportunities are limited for the youth (Zuccato et al. 2011; Dom et al. 2016; Windle, 2018; Mazzette, 2021; 2022). The present analysis highlights the transformation of land use and the emergence of new networks and social relationships related to the cultivation and trade of drugs (Direzione Nazionale Antimafia e Antiterrorismo, 2017).

Logistic and crime operations

From the legal judgements, the second sub-dimension, ‘Logistic and crime operations’, provides a better understanding of drug trade logistics and criminal operations in place. The organisation activity code (131 frequencies, 2 interactions) includes several items such as creating an autonomous network for drug dealing, recruitment for drug dealing, care of the economic and financial aspects, and the search for financing channels and procurement of suppliers, including foreign suppliers. The logistics code (138 frequencies, 1 interaction) includes transport activities by sea (e.g., ferries, fishing boats, boats), roads, trains, and planes.

‘Drug couriers’ are charged with drug possession with the intent to distribute and import illegal drugs (Gonçalves, 2020). The drug courier code (124 frequencies, 1 interaction) refers to the delivery of illegal drugs and the delivery of money obtained by the sales. This code was disentangled into ovuli courier (drug mules) (13 frequencies), which involves an additional hazard to the health and life of the individuals engaged in the drug trade (as complementary criminal effects, RQ2).

A further activity concerns the control of the product, which includes the quality control of the drug (45 frequencies, 2 interactions), such as quantity and price, and the cutting and packaging of the doses. For example, the tasting activity reveals traffickers’ specialisation, like sommeliers.

Money laundering is one of the most common activities for hiding profits derived from the drug trade, involving methods such as transporting cash out of the country or region, purchasing businesses through which funds can be channelled, buying easily transportable valuables, transfer pricing, and even using ‘underground banks’ (Levi and Reuter, 2006; Novaro et al. 2022). According to the legal judgements analysed, money laundering (28 frequencies, 2 interactions) from illegal activities appears to be between 10,000 and 260,000 euros (RQ2).

Local drug dealing

The third sub-dimension involves ‘Local drug dealing’ (251 frequencies, 5 interactions). Local drug dealing includes a set of micro-codes, such as distribution and retail sales intended for the final consumers when a few grams of drugs and a relatively low amount of potential revenue are involved. This code is associated with the offender’s ‘place of birth: South Sardinia’ (47 frequencies, 1 interaction) and victims of crime who are female (frequencies 3, interaction 1) (RQ3). Arguably, this outcome is consistent with the primary location of the Court that issues the judgements with a particular focus on the South of Sardinia (as a province).

Weapons trade

The fourth sub-dimension is the ‘Weapons: guns and explosives’. In the legal documents, the family ‘Weapons’ consists of two macro codes ‘guns’ (35 frequencies; 10 interactions) and ‘explosives’ (8 frequencies, interactions 2). This interconnection helps to respond to RQ2 (complementary crimes and, amongst others, a linkage between the drug trade and weapons).

The macro code ‘Guns’ is linked to several types of drug crimes: cocaine (194 frequencies, 2 interactions), hashish (129 frequencies, 1 interaction) heroin (69 frequencies, 1 interaction) (RQ2). According to Aziani et al. (2021), cocaine and other expensive drugs tend to flow to richer countries where consumers can afford them. High levels of corruption in a country can also drive its involvement in major trade routes, as bribing officials can reduce the risk of arrest and interception for traffickers. This initial cost is outweighed by the long-term economic benefits of easing drug traffic across borders and guaranteeing impunity. Countries with strong institutions and low levels of corruption can impose higher non-monetary costs on traffickers, making it more difficult for them to operate.

Illegal drug seizures involving guns are also associated with offenders who have a consolidated criminal career and have already committed these specific crimes. In this respect, the gun code is associated with the code recidivist offenders (266 frequencies, interaction 1) and aggravating circumstances (285 frequencies, 1 interaction) (e.g., co-offending crime; evidence of prior planning).

From the mid-1980s through the mid-1990s, a global proliferation of guns was observed, and normative diffusion pertaining specifically to crack cocaine markets (Blumstein, 1995). The weapons and drug trade are an important linkage as a defence tool and to perpetrate violent actions (Dorn et al. 2005). However, as highlighted by Pearson and Hobbs (2001) and Calderoni (2012), violence is not good for business because it can raise more attention from media and law institutions and discourage customers. Organised crime groups frequently adopt more subtle strategies (intimidation, 15 frequencies, 2 interactions) that include threats, extortion, and threatening means, sometimes to receive a due payment, sometimes to encourage even self-calumny in Court trials.

The gun is also part of the code ‘crime location: different areas in Sardinia’ (6 frequency, 1 interaction). This outcome implies that illegal gun detention and trade are widespread in the different areas of Sardinia rather than in specific areas, as expected.

Notably, the ‘time frame: 2011–2017’ (90 frequencies, 3 interactions) is associated with the macro-code guns (35 frequencies, 10 interactions) through a strong and bidirectional link. Yet, a strong and bidirectional connection emerges between explosives and the time span between 2006–2010 (291 frequencies, 2 interactions) (right-hand side of the network). This result highlights how the time before the economic crisis seems characterised by different crimes, more linked to using explosives (such as intimidation against individuals or local institutions) and typically more local. Furthermore, there is no connection in previous years, starting from 1997 as the earliest year to which the legal judgements refer (Mazzette, 2021; 2022) has shown the connection between weapons and the drug trade in Sardinia, which is also common in many other countries as a complementary activity (Lim and Morris, 2020; Hughes et al. 2020).

As a further outcome, several legal judgements account for criminal actions unequivocally directed to purchase and keep different types of guns of illegal origin and connected to the drug trade. Sometimes the weapons seized were war-type, such as the Chinese-made AK 47, and automatic weapons model FAL, 7.62. Police also seized guns of various types and calibres, explosive devices, hand grenades, ammunition (e.g., bullets and cartridges), and knives. The weapons, sometimes made by assembling stolen parts, were often used to pay for drug consignments purchased by the ‘Ndrangheta criminal organisation and then sent to Sardinia (RQ2, RQ3). In one court case, for years, the accused had altered an astounding number of standard and war firearms, supplying the organised crime associates, disregarding the ex-post use.

The probabilistic results

As already stated, qualitative information is converted to a quantitative data matrix to better understand the role and interconnections of organised crime groups (RQ2; RQ3). The dependent variable is dichotomous: an organised crime group (i.e., Y1 = 1) or a non-organised crime group (i.e., Y2 = 0), as defined in Eq. 2 and Section 'The case study and the sample'. Estimation robustness is confirmed through the Wald test, with coefficients showing similar signs, magnitude, and statistical significance (Table 2). The unrestricted Model 4 reveals that organised crime groups are more likely to be involved in crimes against persons, including intimidation, premeditation/cruelty, threatening actions, attempted or actual homicide, and committing other crimes for profit. As expected, illegal drug trade is an important factor in the involvement of organised crime groups. The analysis confirms that organisation is essential for the drug trade and that the use and trade of weapons and recidivism increase the likelihood of involvement in organised criminal groups (DIA, 2015; Mastrobuoni and Rialland, 2020).

Table 2 Logistic results: Organised crime groups (yes/no).
Full size table

Discussion and policy implications

Through integrative qualitative and quantitative methods, this paper provides a more comprehensive understanding of OCG’s behaviour, specialisations and policy implications (Roos and Reccius, 2024). The quantitative approach reveals important insights into the drug trade, unveiling drug specialisation among European countries and Italian regions (2011–2019). Belgium denotes the highest share of potential revenues from seizures for cocaine, heroin, and MDMA doses, while Sweden has relatively high amphetamine seizures. Italy prevails for cannabis resin, Greece for herbal cannabis, and Austria for MDMA doses. Besides, the analysis of drug specialisation among Italian regions shows that Calabria has the highest cocaine trade, consistent with the national and international leadership by ‘Ndrangheta. Sicily and Sardinia have the highest hashish potential revenues, while Puglia dominates the national panorama for herbal cannabis. These findings shed light on the scope and magnitude of illegal drugs, which has been historically underestimated due to data limitations (Raineri and Strazzari, 2023; RQ1).

The content analysis of Court judgements uncovers remarkable transformations in criminal activities and regional interconnections, with Sardinia as the new barycentre of national and international drug business (Direzione Nazionale Antimafia e Antiterrorismo, 2017; DIA, 2022). The study uncovers a shift in crime structure, new organisations, and changes in traditional criminal activities (RQ3). The illegal cultivation of cannabis is deeply linked to socio-economic disadvantage in regions lacking legal job opportunities and with a favourable climate, highlighting the connection between land use, criminal activities, and economic relationships (Cocklin et al. 1999; Nelson, 2024). Sardinia’s crime evolution shows new patterns of criminal behaviour, organisation, and weaponry trade and use. These changes are accompanied by increased ties to OCG and investments in money laundering, especially through real estate and hospitality activities in valuable coastal areas (RQ2; RQ3). Among others, these economic sectors are high capital profitability and tourism activity dependent on public financing (DIA, 2022). This transformation process signals a new ‘crime era’ with significant implications for society, legal activities, and the environment (Hughes et al. 2020; Lim and Morris, 2020; Novaro et al. 2022; RQ2).

The probabilistic model underscores the importance of organisational structure in the drug trade and supports the qualitative analysis. These findings highlight the complexity of drug trade networks, revealing significant quantities of drugs and substantial logistical and financial transactions. The involvement of multiple agents, including local affiliates and national and international collaborators, underscores the intricate network operating across different regions and countries, which facilitates and sustains the drug trade while evading law enforcement efforts.

The connections between Sardinian criminal groups and those from other Italian regions, such as Calabria and Campania, as well as from countries like Albania, China, the Netherlands, and Romania, demonstrate the transnational dimension of the drug trade. This international link complicates efforts to combat drug trafficking, necessitating coordinated actions across borders and jurisdictions. Despite the formal hierarchy of mafia groups not being prominent in the drug business, the analysis reveals a clear task division and status differentiation among members. This hierarchical structure ensures the efficiency and effectiveness of drug operations, with roles ranging from leaders and organisers to participants who support criminal activities (see also Calderoni, 2012).

Identified drug routes involving Southern Italy and international locations, such as Venezuela, Portugal, and Spain, underlined a well-established logistics network facilitating the transport, storage and distribution of drugs. The use of various transportation methods, including sea, land, and air, illustrates the adaptability and resourcefulness of these criminal organisations. Additionally, the correlation between the economic crisis (2011–2017) and an increase in drug-related activities suggests that socio-economic factors play a crucial role in fuelling the drug trade. The economic downturn likely pushed more individuals towards drug trafficking as a means of financial survival, highlighting the socioeconomic dimensions of the drug business (Cramer, 2010; Andell et al. 2023; Nelson, 2024).

The role of social ties, including family networks, in supporting drug trade activities emphasises the importance of social relationships in the functioning of organised crime. These ties provide trust and reliability, which are essential for the clandestine nature of illegal activities. To effectively combat the drug trade, policies must address both the organised crime networks and the socio-economic conditions that facilitate their activities. Strengthening the integrity of public institutions to prevent corruption and infiltration by criminal elements is crucial, along with enhancing international cooperation to disrupt transnational drug trafficking networks (Dom et al. 2016; Calaresu et al. 2018).

Given the role of social ties in sustaining drug networks, community-based interventions are vital. Engaging local communities in preventive measures and creating alternative livelihood opportunities can help reduce the socio-economic drivers of drug trafficking. Law enforcement agencies need to adopt multi-faceted strategies that target both the leadership and the operational levels of drug networks. Disrupting the financial flows and logistics that sustain these operations, along with leveraging intelligence and technology to track and dismantle drug routes, is essential (Levi and Reuter, 2006; Novaro et al. 2022). Economic development initiatives and social welfare programmes can provide viable alternatives to criminal activities. The transnational nature of the drug trade necessitates robust international collaboration. Sharing intelligence, harmonising legal frameworks, and conducting joint operations can enhance the effectiveness of efforts to combat drug trade across borders.

The empirical findings also highlight the vulnerability of public institutions to corruption and infiltration by organised crime groups in several ways. On the one hand, the probabilistic modelling reveals that recidivism increases the likelihood of involvement in organised criminal groups. This latter outcome aligns with Mastrobuoni and Rialland (2020), who find that prison inmates who benefited from a pardon are likely to re-offend in groups with prisoners they were released with. They also observe that mafia criminals are the most likely to partner up and commit similar crimes after the pardon or complementary crimes through spillover learning effects during detention. Notably, DIA (2015) remarks on the risk that the presence of individuals with mafia affiliations in Sardinian penitentiary institutions may facilitate contact between mafia organisations and local criminal groups. On the other hand, local public officers are sometimes implicated in drug-related activities. This collaboration between criminals and public officials undermines the rule of law and erodes public trust in governmental institutions, posing a significant threat to civil society (Ruggiero, 2000; Benson and Simpson, 2014; Hataley, 2020; Sergi and Vannucci, 2023). Hence, the increased risk of facilitating contact between mafia organisations and local criminal groups, also through penitentiary officers’ mediation, requires further research and targeted interventions to address these challenges and advance the objectives of UN SDG 16.4.

Raising public awareness about the dangers and consequences of the drug trade and complementary criminal activities, such as money laundering in different economic sectors. can garner public support for law enforcement efforts. Educational programmes targeting vulnerable populations can help prevent the recruitment of individuals into criminal networks (Ashton and Bussu, 2020). Addressing this issue requires a multi-disciplinary approach involving law enforcement, community engagement, socioeconomic development, and international cooperation (Hasan et al. 2024).

The integrative method employed in this research highlights the profound transformations experienced in searching for new venues for consumer-driven illegal trade. In this respect, the economic rational behaviour behind OCG opting for peripheral territories is due to their low risk and high return. This strategy not only maximises profits but can also divert authorities’ attention, allowing larger volumes of illegal and legal activities to be conducted within (RQ3). This finding aligns with Sampó and Troncoso (2023), who show the role of non-traditional harbours in Argentina, Chile and Uruguay as new trade routes for South American narcotrafficking. The insufficient institutionalisation and responsiveness of governance at the national (Italy) and regional (Sardinia) levels may elucidate challenges in addressing criminal activities, including illegal drug markets (Calaresu et al. 2018). This outcome suggests stronger policy frameworks and governance structures to effectively tackle such issues. Tebaldi and Calaresu (2021) argue that territorial policymaking can be shaped by the institutionalisation of the governance system and the quality of territorial policies. Their framework offers prescriptive implications, highlighting best practices for territorial governance to enhance local development in Europe’s periphery. Implementing these practices could enhance the region’s ability to combat illegal drug markets by improving policy frameworks and institutional responsiveness.

Limitations

The present research has several limitations that should be acknowledged to contextualise the findings and guide future research. The analysis relies on data from a single judicial source. Although this Court handles a significant proportion of illegal national and international drug cases in the region of Sardinia, it may not fully represent the dynamics of drug trade and organised crime across different judicial districts.

Besides, the focus on Sardinia, while providing valuable insights into a specific peripheral region, only recently affected by the drug trade and mafia infiltration, may not account for the broader transnational nature of the drug trade. Future studies should consider a comparative approach that examines multiple peripheral regions or countries to understand how local conditions intersect with global drug trade networks and infiltration in the legal economy. Additionally, the reliance on court judgements may introduce biases related to the legal definitions and procedures specific to Italy. Hence, the applicability of these findings to other jurisdictions with different legal frameworks and enforcement practices may be limited. Expanding the research to include comparative analyses with other legal systems could offer deeper insights into the international dimensions of drug trade and organised crime behaviour.

While the study integrates quantitative data with qualitative insights, it still overlooks specific impacts on stakeholders’ experiences, such as affected individuals (e.g. racket, extortion), local institutions and communities (e.g., overall quality of life, well-being) or the intricate social networks within criminal organisations based on shared social capital. Examining these socio-economic impacts could enrich the analysis and provide a more holistic understanding of the drug trade and related crimes.

From a methodological perspective, the study employs an inductive approach that aligns with the theoretical paradigms proposed by Roos and Reccius (2024; see also Oleinik, 2022). However, this approach may limit the ability to generalise the findings or to predict future trends in other contexts. A more deductive approach, using established theories in conjunction with the inductive insights gained from the present research, could enhance the robustness of the conclusions and improve the applicability of the findings to other settings.

Conclusions

The findings of this study hold significant implications for policymakers, particularly in formulating prevention strategies to combat the drug trade and organised crime networks in a peripheral region. Conventional drug law enforcement interventions have shown limited effectiveness (Collins, 2014; Mejía and Restrepo, 2016; Toth and Mitchell, 2018), necessitating a shift towards evidence-based strategies incorporating quantitative and qualitative data (Caulkins, 2017; Reuter, 2017; Bussu and Pulina, 2020). Hence, integrating a more comprehensive theoretical framework that combines orthodox models with interdisciplinary insights could enhance the effectiveness of these strategies (Oleinik, 2022; Roos and Reccius, 2024; Nelson, 2024).

Research in this field can also positively impact the EU drugs strategy 2021–2025 (Council of the EU, 2022; Shulla and Leal Filho, 2023). On the supply side, an effective strategy will require designing and planning specific interventions focused on ‘trade routes’ that will benefit from spatial econometric analyses to understand regional spillover effects. Institutional cross-countries actions will concentrate law enforcement resources on regions with several drug connections, especially those mediating among producers, storage, transit, and final consumers (Calaresu et al. 2018; Tebaldi and Calaresu, 2021). Evidence-based strategies are potentially more effective for preventing international business than non-coordinated interventions (Giommoni et al. 2022).

On the demand side, effort needs to be made to raise awareness amongst communities on the impacts of the drug trade and other complementary crimes (e.g., intimidation, racket, weapons trade, environmental crimes) and in the legal economy through institutional infiltration. As shown in the present study, traditional social control over peripheral territories, once maintained by local communities, is gradually replaced by criminal organisations. Hence, demand-side actions should focus on prevention measures and early interventions, addressing the needs of more vulnerable groups, and supporting comprehensive research and data collection on drug use and its impact.

The present research has adopted a predominantly inductive model consistent with the paradigms proposed by Roos and Reccius (2024). Indeed, the dimensions emerging from the analysis and discussion can serve as the foundation for a more integrated theoretical framework that blends traditional economic theories, such as agents’ rationality, with interdisciplinary insights.