The Investigation and Prosecution of Traffickers: Challenges and Opportunities

  • Rosemary BroadEmail author
  • Julia Muraszkiewicz
Living reference work entry


This chapter will draw on the literature, policy, and research to consider the processes of investigating and prosecuting human trafficking activities across three jurisdictions. The chapter will be split into the following three sections:
  1. 1.

    The United Nations Office on Drugs and Crime Toolkit to combat human trafficking and themes from the UN regarding approaches to perpetrators

  2. 2.

    International initiatives that have developed including those within the European Union, Canada, and the United States

  3. 3.

    A case study of investigation and prosecution in the United Kingdom


These sections are drawn together by identifying learning through the development of best practice along with the challenges that exist in the investigation and prosecution of human trafficking offences.


Human trafficking Prosecution Modern slavery Investigation 


The investigation and prosecution of those responsible for trafficking in human beings is a complex process which involves a delicate balance between securing a successful prosecution and protecting and supporting the needs of those victimized by the activity. These tensions require sensitive, multiagency approaches that operate within a framework which allows for victims’ needs to be prioritized. This is the case with many crimes, although it is heightened in relation to human trafficking based on the multiple vulnerabilities faced by many victims of human trafficking. However, it is often the case that security has been of central focus in legislative and operational approaches to tackling human trafficking, which can leave victim support underdeveloped or difficult to achieve in the context of security, particularly when linked to immigration. Having been a global priority since the mid-1990s, there has been some progress made in understanding how best to coordinate strategy to both successfully prosecute traffickers and appropriately support their victims. Concurrently, challenges remain in achieving the best outcome for all involved.

The aim of this chapter is both to identify the progress that has been made in investigative and prosecutorial processes and to highlight the challenges that remain. The chapter begins at a global level, in firstly considering the themes that initially emerged from the United Nations’ (UN) direction. The next section addresses exemplar initiatives at the European Union (EU) level and national initiatives from Canada and the United States (US) that have derived from this direction and draws out parallels between these approaches that have resulted in common problems with securing successful prosecutions. The final section provides a case study of the United Kingdom (UK) experience which considers the more detailed practical implications, the impact on victims and the challenges encountered by criminal justice professionals in investigating and prosecuting these cases.

The United Nations Office on Drugs and Crime (UNODC) Toolkit (2008) and United Nations’ Themes

In 1998, in an attempt to develop a binding structure on transnational crimes, the UN tasked an ad hoc committee with building a new international legal framework which has become known as the Vienna process (Gallagher 2001). This eventually gave rise to Resolution 55/25 of November 15, 2000, and the adoption of the Convention against Transnational Organized Crime, which sought to tackle organized crime through outlining how states could cooperate on issues such as joint investigations or mutual legal assistance regarding transnational organized crime. The Convention has three additional protocols: (1) the Protocol to Prevent, Suppress and Punish Trafficking in Persons, Especially Women and Children; (2) the Protocol against the Smuggling of Migrants by Land, Sea and Air; and (3) the Protocol against the Illicit Manufacturing of and Trafficking in Firearms, Their Parts and Components and Ammunition.

The motivation for the United Nations’ Protocol to Prevent, Suppress and Punish Trafficking in Persons, Especially Women and Children (henceforth the 2000 UN Trafficking Protocol), was to ensure criminalization of human trafficking. While the 2000 UN Trafficking Protocol was regarded as ground breaking, as it was the first international instrument to define human trafficking (Obokata 2015), it has also been criticized for its over-zealous focus on prosecution over victim protection (Reiley 2006). This chapter also acknowledges that whilst human rights concerns played a role in the negotiations, the question of security was the primary motive for the Protocol (Gallagher 2001). In brief, many states were troubled by the impact that traffickers and smugglers were having on domestic issues. However, the 2000 UN Protocol on Human Trafficking is more than just a tool for protecting state interests. As effectively summarized by Raymond “it creates a global language and legislation to define trafficking in persons, especially women and children; assist victims of trafficking; and prevent trafficking in persons. The anti-trafficking protocol also establishes parameters of judicial cooperation and exchanges of information among countries” (Raymond 2002: 498).

Regarding prosecution of traffickers, Article 5 of the 2000 UN Trafficking Protocol obliged states to adopt legislative and other measures that may be necessary to establish human trafficking as a criminal offence, including participation as an accomplice and the organization or direction of other persons to human trafficking. In addition, subject to the basic concepts of a state’s legal system, attempting to commit the crime is also to be criminalized. Although the Protocol does not prescribe a minimum or maximum sentence, the UNODC (United Nations Office on Drugs and Crime) Model Law against Trafficking in Persons states that “sanctions should fulfil at least the threshold set for trafficking in persons to constitute a serious crime as defined in the Convention, that is, punishable by a maximum deprivation of liberty of at least four years or a more serious penalty” (Article 2 (b) of the Convention (UNODC 2009)).

The UNODC has played an imperative role in elucidating and supporting the 2000 UN Trafficking Protocol and thus, among other things, advising on the process of how best to investigate and prosecute the crime of human trafficking. This has partly been achieved through the UNODC Toolkit to Combat Trafficking in Persons of 2008 (2nd edition), which collected and disseminated successful practice in order to facilitate the sharing of knowledge and information among policymakers, law enforcers, judges, prosecutors, victim service providers, and members of the civil society working at different levels toward the overall aim of preventing and combating human trafficking, protecting trafficked persons, and promoting international cooperation.

The key lessons learned from the operationalization of the toolkit (for not all the findings can be echoed and analyzed here, see Perrin 2010) are threefold (UNODC 2008). Firstly, it is the narrative of the toolkit that all law enforcement responses must be holistic, taking into consideration a range of issues, from the rescue of victims and the protection of witnesses to the prosecution of traffickers. As such, all law enforcement persons should cooperate with other relevant stakeholders such as civil societies working with victims, local authorities who may house victims, or labor inspectors.

Secondly, the toolkit (UNODC 2008) signposts that direct witnesses of a crime are a crucial element of a successful prosecution. Consequently, most national and international documents addressing human trafficking recognize that the process of building a case and delivering a successful prosecution are more effective when the victim has continued presence in the country. Thus provisions are made to enable residence for victims, who are irregular migrants. There is an understandable truism in that much of the evidence rests on what the trafficked persons say, and that is why trafficking investigations and prosecutions require that law enforcement officials work to establish a trusting relationship with the victim. However, this is not without challenges due to distrust of law enforcement agencies and fear that they may be prosecuted for crimes they were compelled to commit in the course of the trafficking situation (discussed further below). Some victims refuse to cooperate, some are too traumatized, and they disappear or are re-trafficked. To address this, there are moves to run “victimless prosecutions,” which in the United Kingdom have been used in cases of domestic violence (see Lee Stewart Barnaby v The Director of Public Prosecutions [2015] EWHC 232). At the time of writing, there was one case in the United Kingdom of a victimless prosecution under the Modern Slavery Act, concerning human trafficking for the purposes of sexual exploitation (see Open Minds Foundation 2016 for a discussion on this point).

Lastly, the toolkit (UNODC 2018) places increased emphasis on training and training resources to reinforce law enforcement and peacekeepers’ ability and capacity to respond to human trafficking. This is now an accepted practice. However, it is important to acknowledge that training is required far beyond the law enforcement domain. Undeniably, a large group of persons remain outside the “authorities’ field of vision” (Rijken and Koster 2008: 6). Yet an important aspect in reducing human trafficking is precisely the ability to recognize it, support those affected, and find an appropriate and long-term approach for their recovery. It is consequently suggested that a professional likely to be working with a potential trafficked person needs to “be aware of what facts may point to the client having been trafficked and to be aware of what to do when they are alerted to the possibility that this may be the case” (Drew 2009: 3). This is pertinent to frontline staff, such as medics, teachers, and staff from local authorities and those working on distribution of benefits. They are often the first to see victims. Thus, they need to be equipped with up-to-date knowledge and skills surrounding the crimes, to optimally respond to potential victims. This is evidenced by the European Directive 2012/29/EU (Art. 25) and Directive 2011/36/EU, which recommend the adoption of training and education mechanisms for workers in sectors most likely to meet potential victims/perpetrators. In turn, this may help with the investigation and prosecution of traffickers, although the onus largely remains on victim evidence and participation.

(Resultant) International Initiatives

This section is focused on the way in which the global framework has translated into approaches on a smaller scale. The discussion below is shaped around EU, US, and Canadian approaches to prosecution to highlight shared challenges and successes in building frameworks to successfully respond to human trafficking as well as identifying divergence in these initiatives.

The EU

Significant investment of resources and time, through consultations and drafting, has been dedicated to respond to a crime that the European Commission (EC) has described as “a serious crime against persons” (European Commission 2005: 1). Directive 2011/36/EU of the European Parliament and of the Council of 5 April 2011 on preventing and combating trafficking in human beings and protecting its victims represents the focus of the EU strategy to addressing human trafficking. It is based on the three P-paradigms: prosecution, protection, and prevention; and resultant state obligations in the directive concern all three aspects. The Directive is progressive in an increased focus on victim protection (Art. 8, 11–17) and action to prevent the crime (Art. 18). Article 2 which provides the definition of human trafficking obliges states to take the necessary measures to ensure that human trafficking is punishable. The Directives return to investigation and prosecution in Article 9 which obliges states to ensure that investigation into or prosecution of human trafficking is not dependent on reporting or accusation by a victim and that criminal proceedings may continue even if the victim has withdrawn his or her statement. Again, this showcases the importance of due diligence in gathering evidence and a departure from the initial global emphasis, described above, where the victim was key to prosecutions. This is essentially making him/her more of a witness than a person deserving of rights. It is argued here that law enforcement and prosecutors need to move beyond “traditional” investigation, and as stated by Gallagher, “due diligence may also require that investigators do not just rely on complaints from victims but actually go out and investigate on their own” (Gallagher 2010: 384).

The Directive’s approach does appear to distance itself from linking victim protection with compulsory assistance, from the victim, in the prosecution process. Paragraph 18 of the Recital states that “a person should be provided with assistance and support as soon as there is a reasonable-grounds indication for believing that he or she might have been trafficked and irrespective of his or her willingness to act as a witness.” The same is found in Art. 11(3): “Member States shall take the necessary measures to ensure that assistance and support for a victim are not made conditional on the victim’s willingness to cooperate in the criminal investigation, prosecution or trial, without prejudice to Directive 2004/81/EC or similar national rules.” This importantly limits the discretionary powers of the states in which assistance and support can only be granted if the victim cooperates with the authorities in criminal proceedings. However, as above, Article 11(3) also states that unconditional access to support is without prejudice to Directive 2004/81 or any similar national rules. In short, Directive 2004/81 grants a temporary residence permit to third-country nationals who are a victim of human trafficking and who cooperate with the authorities. This means that based on this Directive, trafficked victims can only access support and assistance provided in accordance with this Directive if they cooperate with the authorities and is limited to the duration of criminal proceedings only. This seems to be in full contrast with the unconditional access articulated in Article 11 (3).

Further, Paragraph 14 of the Recital reads that the aim of the non-prosecution and non-punishment principle (found in Art. 8) “is to safeguard the human rights of victims, to avoid further victimization and to encourage them to act as witnesses in criminal proceedings against the perpetrators” (emphasis added). It seems incongruous to, on one hand, state that protection is not linked to prosecution and on the other state that protection is carried out to encourage successful prosecutions.

Troublingly for the EU, successful prosecution of trafficking cases remains a challenge. The European Commission’s 2016 report on the progress made in relation to human trafficking analyzes the main actions undertaken by states (report as required under Article 20 of Directive 2011/36/EU on preventing and combating trafficking in human beings and protecting its victims). According to the report, the level of prosecutions and convictions remains worryingly low, especially when compared to the number of victims identified (European Commission 2016). The cases are often complicated and have a transnational aspect and poor evidence. To facilitate successful prosecution, the Commission encouraged Member States to establish national multidisciplinary law enforcement units on human trafficking which should closely cooperate with Europol and be able to exchange information with local, regional, and national law enforcement units (European Commission 2016). Furthermore, Member States are encouraged to increase cross-border police and judicial cooperation in trafficking cases and make use of all relevant avenues for such cooperation and in particular the establishment of joint investigation teams (JIT) and using Europol and Eurojust (the European Union’s Judicial Cooperation Unit). The European Commission (2016) also encouraged the use of corroborative evidence including financial investigations, which should be proactively conducted in all trafficking cases. These recommendations have the potential to shift the burden of successful prosecution away (or at least to share it with) trafficked victims toward a broader spectrum of evidence.


Human trafficking has become a significant policy issue for successive Canadian governments. A review of legislation in 2005 found that the legislation favored “preventative and prosecution measures but fail[ed] to provide protection to the basic rights of trafficking victims” (Oxman-Martinez et al. 2005a: 30). This reflected the global focus on security as opposed to human rights although an early review of the situation in Canada highlighted the need to work effectively with countries of destination to target the “structural causes of human trafficking” (Bruckert and Parent 2002: 26). Canada was among the first set of countries to ratify the Protocol, and the 2012 National Action Plan to Combat Human Trafficking (the Action Plan) (Government of Canada 2012) represented the first action plan of this kind for Canada, formally documenting Canada’s anti-trafficking approach. The Canadian government began by developing tools for the prosecution of traffickers, in line with the recommendations of the Protocol (Oxman-Martinez et al. 2005b). In 2012 the legislation was introduced to prosecute Canadians for human trafficking offences while not in Canada (Bill C-310 Criminal Code of Canada) building on legislative amendments in 2010 which increased minimum sentences from 2 to 5 years. A former private member’s bill was introduced into the Canadian legislation in early 2017 which amended previous anti-trafficking legislation with the aim of giving “law enforcement and prosecutors new tools to better investigate and prosecute human trafficking offences” (Government of Canada 2017a). One of these tools in this recent legislation facilitates the proving of the element of control over a victim through evidence of the perpetrator living with the victim or being habitually with them as evidence of control. The legislation also placed the onus on traffickers to prove that their property was not proceeds of crime and made it easier for proceeds of crime to be seized.

The Action Plan and the Criminal Code of Canada recognized the necessity of measures to “make testifying less traumatic for victims” (Government of Canada 2012: 8) and introduced testimonial aids such as the ability to testify from an alternative location to the court room and support of other people (such as victim support representatives) while testifying. Trafficked victims are not required to provide evidence in court to gain temporary or permanent residence. Additionally, free legal advice was introduced for victims in Ontario in 2018 (Malo 2018) having been previously recommended by victim service providers (Oxman-Martinez et al. 2005a). In relation to prosecution, the Action Plan highlighted targeted training and the establishment of a dedicated integrated investigative team (the importance of cross-sector collaboration has also been highlighted in research elsewhere; see Winterdyk 2017). This multiagency model reflects policy developments in the United States and the United Kingdom discussed below that are considered to strengthen anti-trafficking initiatives. The Action Plan acknowledged the small number of convictions at the time of publication which numbered 25 convictions specifically for human trafficking offences between 2005 and the publication of the Action Plan in 2012.

The first successfully prosecuted human trafficking case in Canada is known as the Domotor case and was “hailed as a significant milestone in the fight against human trafficking in Canada” (Hastie and Yule 2014: 83). The case involved a large group of “organized” criminals who exploited 19 known victims in their construction company. However, Hastie and Yule (2014) were cautious regarding the impact of and successes highlighted in this case. They identified gaps in the response to human trafficking cases revealed by the case: the lack of victim support for male victims and issues related to the provision of interpreters and translators during the criminal justice process. The case particularly highlighted the focus of the Action Plan as “nearly entirely on a crime-control approach…and makes no commitment in respect of service provision” for victims (Hastie and Yule 2014: 91).

Since its inception, the Action Plan has been reviewed annually to evaluate and monitor the progress made. The 2016–2017 horizontal evaluation of the Action Plan identified progress in terms of awareness raising and victim support. However, investigation and prosecution remained more challenging areas due to constraints across different jurisdictions such as differences in local practice and information sharing and difficulties in gathering evidence (Government of Canada 2017b) further complicated by the investigation and prosecution of trafficking cases at a provincial and federal level. The Action Plan was evaluated against the aims of establishing a dedicated integrated enforcement team, providing training and education for criminal justice professionals, and enhancing intelligence collection and coordination. The evaluation found that the number of charges, prosecutions, and convictions remained low (a similar problem to the EU, as above): there were 307 human trafficking cases from 2012 to 2016 and 45 human trafficking-specific convictions. The difference between the number of cases and convictions represents patterns elsewhere and exemplifies the challenges for law enforcement in pursuing human trafficking investigations. The evaluation found that victims remained “reluctant to testify for fear of reprisals by the traffickers” (Government of Canada 2017b) despite progress made in terms of victim support. However, the Action Plan does not identify any specific and measurable action points in relation to investigation and prosecution.

In common with other jurisdictions, “despite the adoption of legal mechanisms, Canada has faced major challenges when prosecuting human trafficking” (Winterdyk 2017: 223). Millar et al. (2017) identified several problems with both researching the investigation and prosecution process (lack of available information, lack of understanding of human trafficking by criminal justice professionals, and lack of consistency in definitions in reporting offences) as well as with the process itself. Trying to discern information relating to the progress of the case from charge to prosecution illustrated “how challenging it is to obtain and triangulate primary legal data in Canada” (Millar et al. 2017: 48), the experience of which has been reflected in the United Kingdom (see Gadd et al. 2017). Given the low numbers of convictions and issues with prosecution, “Canadian trafficking case law developments are in their early stages” (Millar et al. 2017: 34). Police have encountered “significant barriers to obtaining cooperation from victimized individuals” particularly as the individual often faces job loss and deportation (Winterdyk 2017: 222).

The Trafficking in Persons Report (2018: 130) identified Canada as a tier 1 country stating that the Canadian government had “continued to demonstrate serious and sustained efforts during the reporting period.” However, the report also identified problems in relation to convictions by the Canadian government, particularly with regard to convictions for labor-related exploitation, noting a “continued imbalance in the government’s anti-trafficking efforts, with greater attention to and understanding of sex trafficking versus forced labor”(2018: 131). As in other places, the dominant construction of human trafficking as a problem of the sexual exploitation of women and girls has caused problems for the identification and investigation of other types of trafficking (Winterdyk 2017; Spencer and Broad 2012). The continued focus on sexual exploitation noted here in Canada and reflected in other areas is problematic as where victim experiences “fall outside the narrow criminal justice mandate and resource allocation…[they] may not be able to access services that are tied…to some form of criminal investigation” (Winterdyk 2017: 228).

Despite a long-standing commitment to the problem of human trafficking, Canada has continued to encounter problems at a practical and legal level relating to successful prosecutions for specific trafficking offences. The progress has been made in relation to the development of multiagency approaches, but the continued centrality of law enforcement in anti-trafficking discourse is problematic. “Despite a legally untested definition and a limited number of criminal cases, law enforcement and criminal justice actors have largely shaped discussions of human trafficking and responses to trafficking in Canada” (Winterdyk 2017: 221). There therefore remains a need for increased coordination with other agencies (Kaye et al. 2014).

The United States

The Trafficking Victims Protection Act (TVPA) was passed in 2000, and the TVPA Reauthorization Act 2008 required states to legislate for criminal prosecution of trafficking to continue any humanitarian and assistance to those states, further incentivizing those states to take positive action. The US Government encouraged the development of state-level anti-trafficking legislation such that all states now have relevant trafficking laws to “give the local police the tools necessary to be actively involved in the detection, arrest and prosecution of traffickers” (Schauer and Wheaton 2006: 159). The Annual Trafficking in Persons (TIP) Reports produced by the US Department of State (see US Department of State 2018 for the most recent report at the time of writing) categorize countries into tiers based on the extent to which human trafficking is recognized as a problem, the efforts made to address the problem of human trafficking, and the extent to which the countries’ efforts meet the minimum requirements of the TVPA. In 2007, the Department of Justice (DOJ) formed the Human Trafficking Prosecution Unit (HTPU) as a specialized unit to deal specifically with complex human trafficking cases of national significance (DOJ 2017). As above, pressure placed on jurisdictions through the tiering system of the TIP reports and the contingence of assistance because of anti-trafficking measures places the United States at the forefront of anti-trafficking approaches. The dominant position of the United States in the current anti-trafficking discourse has been said to “force other countries to get serious about prosecuting cases of slavery” (Allain and Bales 2012: 1).

Despite progress made and the significance of US policy and legislation, little is known about the effectiveness of anti-trafficking strategy in the United States and the consistency of efforts across states (Farrell et al. 2013). As in other countries, the numbers of prosecuted cases across the United States remains low (there were approximately 1876 prosecutions for federal human trafficking and 450 at state level between 2000 and around 2016 (Farrell et al. 2016)). There are issues with the investigation of human trafficking cases at a local level with the majority of cases involving trafficking for sexual exploitation of US citizens. The few perpetrators that are charged are frequently charged with lesser offences where the penalties are less severe (Farrell et al. 2013). The relatively infrequent use of the legislative tools has meant that prosecutors are unfamiliar with the legislation and this is especially the case with trafficking for labor exploitation, where the numbers are smaller still (Farrell et al. 2013). Due to the dual criminal justice system in the United States (in a pattern similar to that identified in Canada, above), this is compounded at state level, where state prosecutors have less experience of human trafficking cases than at the federal level (Farrell et al. 2016). Lastly, there is a lack of specialist units dedicated to the problem of human trafficking, particularly in smaller areas (Farrell et al. 2013; Reid 2012).

The National Strategy to Combat Human Trafficking (US Department of Justice 2017) identified bringing human traffickers to justice as one of the priorities for the DOJ through (among other measures) strengthening multiagency partnerships and capacity building for victim support, as observed in the discussion regarding EU and Canada above. Here, it is worth bringing to attention the Human Trafficking Task Force e-Guide, hosted by the Office for Justice Programs website (US Department of Justice 2018). The Office of Justice Programs (OJP) provides innovative leadership to federal, state, local, and tribal justice systems, by disseminating state-of-the art knowledge and practices across the United States and providing grants for the implementation of these crime-fighting strategies. The ethos of this tool is well described on the website stating that it is impossible for any single agency or organization to respond comprehensively to the problem of human trafficking. The e-Guide acknowledges that traffickers’ range from opportunistic individuals to sophisticated criminal organizations, with multijurisdictional activity. The resulting victimization is described as extreme and involving diverse populations with a host of needs. The response to human trafficking is described as most effective, coordinated, and efficient through multidisciplinary and collaborative problem-solving efforts. The guide is in comprehensive language, but not at the cost of being superficial, and provides excellent information on what is human trafficking; how to form a task force; how to operate a task force (including community-based partnerships and information sharing); what supporting victims ought to entail; who are the victims (uniquely including information on LGBTQ victims and victims with physical, cognitive, or emotional disabilities); how to build strong cases; and the role of courts (including ethical consideration and use of innovative court responses). This guidance may provide a useful template for countries at the stage of developing anti-trafficking tools.

Following the Justice for Victims of Trafficking Act, all US attorneys’ offices have developed local strategies to improve victim identification and the investigation and prosecution of human trafficking crimes (DOJ 2017). Within this framework, the strategies identify the importance of using evidence other than or in addition to that provided by the victim, similar to recommendations made in the EU (European Commission 2012). However, there remains a greater burden on victim evidence. The dependence on victim testimony combined with the complex relationships between traffickers and their victims results in problems with prosecutions (Farrell et al. 2013). Elsewhere, Farrell and colleagues (Farrell et al. 2016: 52) highlight that “extra-legal factors such as suspect and victim characteristics and the victim’s relationship to the suspect also influence the decision to prosecute a case.” This is similar to what happens in a domestic violence case. Unsurprisingly, there is a worry that where victims do not fit the ideal image of what a victim ought to look like (a weak, passive female who did not contribute to the crime done against her), prosecutors will decide not to prosecute, thus denying the victim a chance of justice (Srikantiah 2007).

In the abovementioned Human Trafficking Task Force e-Guide, the chapter on building strong cases begins with victim-centered investigations, illustrating how the role of the victim remains key. The e-Guide states that victims are crucial to human trafficking investigations and prosecutions. In many human trafficking cases, only the victim can explain the coercion and control that is a basic element of the crime of human trafficking. As discussed, this is of course true, but it does risk victims becoming a tool to a state-focused end of increasing levels of prosecutions. The e-Guide however is revolutionary in its attempt to consider how to ensure victim involvement in a way that guards the victim’s dignity, for instance, by empowering victims and providing them with recourses that could help the victims tell their stories. This is certainly a more preferred avenue than for instance offering them advantages such as residence permits in exchange for cooperation. The latter is a tactic that may backfire: “[i]t has been pointed out that offering residency conditioned upon testifying can backfire in court and provide opportunity for the defence to draw into doubt the veracity of the testimony, or indeed, even induce exaggeration of information in order to obtain a residence permit” (Brunovskis and Skilbrei 2016: 18). Of note however is that across the United States, suspects are more likely to be charged where there is additional evidence to corroborate the victim’s evidence (Farrell et al. 2016) which may indicate a movement away from a narrow reliance on victim testimony alone or alternatively may exemplify the doubt which can meet testimony of victims where there is no additional supporting evidence.

Investigation and Prosecution Case Study of the United Kingdom: Challenges and Best Practice

England and Wales’ 2015 Modern Slavery Act (hereinafter MSA) was the result of a wave of new governance around efforts to address human trafficking and slavery. The legislation aimed to consolidate existing offences, simplify the legislation, and provide stakeholders with relevant tools and powers to fight the crime. It also required UK companies with a turnover above £36 million per annum to produce a statement setting out how they ensure modern slavery is not taking place in their business or their supply chains. The act also created the Independent Anti-Slavery Commissioner. The role of the Commissioner is to identify and promote best practice in anti-trafficking responses as well as to drive improvement across these responses in the United Kingdom and internationally. However, the first Commissioner resigned in May 2018 citing government interference in his role (Press Association 2018) and illustrating additional problems with the governance of the problem of human trafficking (Broad and Turnbull 2018).

The development of the MSA has marked a diversion, particularly in terminology, within the EU frame although other Member States are in the process of developing “modern slavery” legislation (e.g., France, along with other, non-EU countries such as New Zealand and Australia (Broad and Turnbull 2018)). Among other changes, the Act has replaced previous legislation that fell under several different acts under a single act (for an overview of UK policy development, see Broad and Turnbull 2018; Craig 2017). The legislative changes were partially prompted by recognition from those working within the sector of the poor levels of victim protection and support, particularly through investigative processes (through the anti-trafficking monitoring group’s collaborative report: (ATMG 2013), also see CSJ 2013). The report found that the previous disparate legal framework was “confusing and potentially misleading” (ATMG 2013: 10). This had resulted in a disproportionately low number of convictions for trafficking offences as well as the inability of trafficked victims to access adequate protection as required through the 2005 Council of Europe Convention on Action against Trafficking in Human Beings and European Union Directive 2011/36. In addition, the issue of balancing victim support with migration concerns had previously led to criticism of the commitment to victim care in the context of the removal of undocumented migrants (Balch and Geddes 2011). A context where victims are unsure of their ability to access support and what the implications of reporting their victimization may be will prevent their participation in the investigative process.

The MSA aimed to increase the numbers of prosecutions and convictions, particularly through international cooperation, working with partners, and by providing better support for victims and witnesses through court proceedings (HM Government 2015). However, reports released at the end of 2017 and early 2018 indicated little improvement. In particular, a report from the National Audit Office (NAO) (2017) on public spending on reducing modern slavery stated that although the United Kingdom had an identification and support system in place (the National Referral Mechanism (NRM)), there are numerous shortcomings. The criticisms concern victim care, including that the Home Office has been very slow to implement improvements to the NRM, despite recognizing a series of problems in 2014 (NAO 2017: Para. 14). In addition, NRM decisions on whether the person has sufficient evidence to be identified as a victim are slow, causing distress and anxiety to vulnerable people in the NRM system (NAO 2017: Para. 16). Decisions are made by trained individuals who work for “competent authorities” or first responders including the police, UK Border Force, Home Office Visas and Immigration, and several anti-trafficking NGOs. In recognition of problems with the NRM decision-making system, a pilot scheme was introduced and evaluated in 2017 (Home Office 2017). The decision-making within the pilot involved a more specifically trained and experienced decision-maker charged with making the decisions. The pilot was evaluated with generally positive results although this system has not yet been implemented at the time of writing (see Home Office 2017 for more information). Regarding prosecution the key conclusion is that there have been few prosecutions and convictions under the MSA, again similar to trends elsewhere. The report states that:

in 2016, only 80 defendants were prosecuted under the Modern Slavery Act for 155 modern slavery offences, rising from 26 in the previous year for 27 offences. This legislation can only be used for crimes committed after the Act was introduced and as modern slavery cases take a long time to build (two to five years) it is difficult to benchmark. There has been increasing use of the Modern Slavery Act to prosecute defendants, although the overall volume of prosecutions related to modern slavery is relatively small. In 2016, there were 349 completed prosecutions of defendants flagged by the CPS (Crown Prosecution Services) as being involved in modern slavery, of which 62% resulted in conviction. Despite this conviction rate being in line with other hidden crimes, a small proportion of the crimes recorded by the police result in a charge. The average length of a custodial sentence for modern slavery between 2014 and 2016 was around four years. The Modern Slavery Act has set the maximum sentence to life in prison, but that sentence has not yet been used. (NAO 2017: Para. 21)

This effectively summarizes the consistent and continuing problems with investigative and prosecutorial processes in the United Kingdom but also reflects themes identified throughout this chapter in other jurisdictions.

Undeniably cases on human trafficking are complex and include numerous actors, transnational networks, missing witnesses, and frequently inexperienced law enforcement officials. Another reason that cases of human trafficking are complex to prosecute is the fact that they do not only entail criminal law but also administrative law, international cooperation, and complex financial investigations. In response to this, the Group of Experts on Action against Trafficking in Human Beings (GRETA) (2014) encouraged the specialization of judges. A previous GRETA report (2012) stated that an increase in training of those involved in the prosecution process could improve effective evidence collection and subsequently increase related prosecutions in the United Kingdom. These recommendations have been promulgated by a range of experts but have been slow to be implemented.

A final problem concerns financial investigations as part of the criminal investigations – related financial investigations are few even though investing in better financial investigations would benefit the possibilities of forfeiture, which could ideally benefit the victim. According to the European Commission (2012: 9–10), “[e]vidence gathered from money trails might provide the necessary additional proof, particularly in high-risk sectors, thus relieving victims of the burden of testifying in court.” The United Kingdom has existing money laundering offences under the Proceeds of Crime Act 2002 (POCA) that can be used to disrupt criminal finances. There are also separate regulations that protect the financial sector and other related businesses from being used for money laundering and help to identify suspicious financial activity. The POCA also has various means to recover the financial benefits made through any crime, namely, confiscation following any criminal conviction, civil recovery in the High Court, cash forfeiture in the magistrates’ courts, and taxation. The legislation also provides specific investigation powers to ascertain the extent and whereabouts of the proceeds of crime. The key is thus to raise awareness and encourage the use of legal provisions that allow for financial investigations and recovery of criminal assets. Efforts should be put into integrating financial investigations into trafficking cases on a regular basis (Keatinge 2017).


This chapter has aimed to provide a review of the investigation and prosecution of human trafficking cases to identify themes in relation to challenges and progress in this regard. The forefronting of the international policy frame as more focused on security than human rights from the outset appears to have had long-term implications in framing national responses. Starting from a point of law enforcement and prosecution has led many countries to identify that their approaches to victim protection were lacking in support. However, incorporating effective victim protection at the same time as necessarily pursuing prosecutions has proven difficult. While some progress has been made in this area in relation to multiagency working and capacity building for victim support services, there remain significant barriers to providing effective levels of support that enable victims both to have the necessary support to recover from their victimization and also to work with the criminal justice system to assist in successful prosecution.

Despite positive changes in the investigative process and as acknowledged at all levels, from the global to the local, law enforcement is only one very small part of a much bigger picture. Wider structural inequalities must be tackled to provide better opportunities in countries of origin for those who eventually find themselves bound up in human trafficking activity – for both victims and perpetrators. Encouraging participation in the prosecutorial process for victims who may ultimately find themselves returned to their country of origin is not a viable option if there are no legitimate work opportunities in those countries. Philosophically treating victims as witnesses rather than as person’s who are owed rights is problematic. In addition, failing to develop adequate frameworks of rehabilitative work (a discourse that receives very little attention) with those who have perpetrated these crimes may see them returned to the same networks and needs that they had prior to prosecution.

The move toward multi-agency models partly recognizes the need for a coordinated approach to build the frameworks necessary to adequately support victims and identify effective evidence to prosecute traffickers. It also acknowledges the futility of trying to understand the picture from a national level: while it is important to piece together information to build a wider view, learning from the local manifestation of human trafficking activity and the successes and challenges facing local collaborations can effectively inform national strategy, as much as a top-down approach (also see Winterdyk 2017). Those who are working in anti-trafficking on a daily basis are often those with the most knowledge, and these views are vital in developing policy.

According to this review, there are significant challenges in the operationalization of anti-trafficking legislation. In considering the implementation of legislation, Farrell et al. (2013: 141) state that legislation does not necessitate or explicate operational change, “unless criminal justice organizations actively seek change…there will be a lag or even a complete disconnect between the enactment and the enforcement of new laws.” The enactment of legislation can only represent the start of the process. As illustrated across jurisdictions, local experience of working with the (inter)national guidance to achieve successful outcomes in trafficking cases is a work in progress.


  1. Allain J, Bales K (2012) Slavery and Its Definition. Global Dialogue 14 2. Available Accessed 11 May 2018.
  2. Anti-Trafficking Monitoring Group (2013) In the Dock: Examining to UK’s Criminal Justice Response to Trafficking. Anti-Trafficking Monitoring Group. Available Accessed 1 Oct 2018.
  3. Balch A, Geddes A (2011) Opportunity from crisis: Organisational responses to human trafficking in the UK. The British Journal of Politics and International Relations, 13: 26–41.CrossRefGoogle Scholar
  4. Broad R, Turnbull N (2018) From human trafficking to modern slavery: The development of anti-slavery legislation in the UK. European Journal on Criminal Policy and Research.
  5. Bruckert C, Parent C (2002) Trafficking in human beings and organized crime: A literature review. Royal Canadian Mounted Police, Research and Evaluation Branch. Available Accessed 17 May 2018.
  6. Brunovskis A, Skilbrei M L (2016) Two birds with one stone? Implications of conditional assistance in victim protection and prosecution of traffickers. Anti-Trafficking Review 6: 13–30.Google Scholar
  7. Centre for Social Justice (CSJ) (2013) It Happens Here: Equipping the United Kingdom to fight modern slavery, a policy report by the Slavery Working Group The Centre for Social Justice: London.Google Scholar
  8. Craig G (2017) The UK’s modern slavery legislation: An early assessment of progress. Social Inclusion 5(2): 16–27.CrossRefGoogle Scholar
  9. Department of State (2018) Trafficking in Persons Report 2018. Department of State: United States of America. Available Accessed 1 Oct 2018.
  10. Drew S (2009) Human trafficking – human rights. London: Legal Action Group.Google Scholar
  11. European Commission (2005) Fighting trafficking in human beings – an integrated approach and proposals for an action plan. Available Accessed 1 Oct 2018.
  12. European Commission (2012) The EU strategy towards the eradication of trafficking in human beings. Available Access 1 Oct 2018.
  13. European Commission (2016) Report from the Commission to the European Parliament and the Council on the progress made in the fight against trafficking in human beings. Available Accessed 1 Oct 2018.
  14. Farrell A, DeLateur M, Owens C, Fahy S (2016) The prosecution of state-level human trafficking cases in the United States. Anti-Trafficking Review 6: 48–70.Google Scholar
  15. Farrell A, Owens C, McDevitt J (2013) New laws but few cases: Understanding the challenges to the investigation and prosecution of human trafficking cases. Crime, Law and Social Change 61(2): 139–168.CrossRefGoogle Scholar
  16. Gadd D, Broad R, Craven J, Lightowlers C, Bellotti E (2017) Mapping the contours of modern slavery in Greater Manchester. Available Accessed 1 Jun 2018.
  17. Gallagher A (2010) The international law of human trafficking. Cambridge University Press, New York.CrossRefGoogle Scholar
  18. Gallagher A (2001) Human rights and the new UN Protocols on trafficking and migrant smuggling: A Preliminary Analysis. Human Rights Quarterly 23(4): 975–1004.CrossRefGoogle Scholar
  19. Government of Canada (2017a) Strengthening Canada’s criminal law response to human trafficking. Department of Justice, Government of Canada. Available last accessed 15/05/18.
  20. Government of Canada (2017b) Horizontal evaluation of the national action plan to combat human trafficking. Department of Justice, Government of Canada. Available Accessed 15 May 2018.
  21. Government of Canada (2012) National action plan to combat human trafficking. Department of Justice, Government of Canada. Available Accessed 15 May 2018.
  22. Group of Experts on Action against Trafficking in Human Beings (GRETA) (2014) Report concerning the implementation of the Council of Europe Convention on Action against Trafficking in Human Beings by the Netherlands. GRETA. Available Accessed 15 May 2018.
  23. GRETA (2012) Report concerning the implementation of the Council of Europe Convention on Action against Trafficking in Human Beings by the UK. GRETA. Available Accessed 15 May 2018.
  24. Hastie B, Yule A (2014) Milestone or missed opportunity? A critical analysis of the impact of Domotor on the future of human trafficking cases in Canada. Appeal 19: 83–93.Google Scholar
  25. HM Government (2015) Modern Slavery Strategy. HM Government, London. Available Accessed 1 Oct 2018.
  26. Kaye J, Winterdyk J, Quarterman L (2014) Beyond criminal justice: A case study of responding to human trafficking in Canada. Canadian Journal of Criminology and Criminal Justice 56(1): 23–48.CrossRefGoogle Scholar
  27. Keatinge T (2017) Following the financial footprints: New approaches to disrupting human trafficking and modern slavery. The European Review of Organized Crime 4(2): 128–146.Google Scholar
  28. Malo S (2018) In a first for Canada, trafficking victims get free legal help. Reuters News. Available Accessed 15 May 2018.
  29. Millar H, O’Doherty T, Roots T (2017) A formidable task: Reflections on obtaining legal empirical evidence on human trafficking in Canada. Anti-Trafficking Review 8: 34–49.Google Scholar
  30. National Audit Office (2017) Reducing modern slavery. Available Accessed 15 May 2018.
  31. Obokata T (2015) Human trafficking. In: Boister N, Currie R (eds) Routledge Handbook of Transnational Criminal Law. Routledge, London and New York.Google Scholar
  32. Open Minds Foundation (2016) The UK coercive control law and victimless prosecution. Open Minds Foundation. Available Accessed 01/01/18.
  33. Oxman-Martinez J, Lacroix M, Hanley J (2005a) Victims of trafficking in persons: Perspectives from the Canadian community sector. Department of Justice: Canada.Google Scholar
  34. Oxman-Martinez J, Hanley J, Gomez F (2005b) Canadian policy on human trafficking: A four-year analysis. International Migration 43 (4): 7–29.CrossRefGoogle Scholar
  35. Perrin B (2010) Just passing through? International legal obligations and policies of transit countries in combating trafficking in persons. European Journal of Criminology 7(1): 11–27.CrossRefGoogle Scholar
  36. Press Association (2018) Home Office under fire over ‘muddled strategy’ on slavery that fails victims. The Guardian. Available Accessed 6 Jun 2018.
  37. Raymond J (2002) The New UN trafficking protocol. Women’s Studies International Forum 25(5): 491–502.CrossRefGoogle Scholar
  38. Reid J (2012) Rapid assessment exploring impediments to successful prosecutions of sex traffickers of US Minors. Journal of Police Criminal Psychology 28(1): 75–89.CrossRefGoogle Scholar
  39. Reiley A (2006) Trafficking in human beings: A comparative account of legal provisions for combating trafficking in Belgium, Italy, The Netherlands, Sweden and The United States. In: Van Den Anker C, Doomernik J (eds) Trafficking and Women’s Rights. Palgrave, Basingstoke, p 89–117.Google Scholar
  40. Rijken C, Koster D (2008) A human rights based approach to trafficking in human beings in theory and practice.
  41. Schauer E, Wheaton E (2006) Sex trafficking into the United States: A literature review. Criminal Justice Review 31(2): 146–169.CrossRefGoogle Scholar
  42. Srikantiah J (2007) Perfect Victims and Real Survivors: The iconic victim in domestic human trafficking law. Boston University Law Review 87: 157–211.Google Scholar
  43. Spencer J, Broad R (2012) The groundhog day of human trafficking for sexual exploitation debate: New directions in criminological understanding. European Journal on Criminal Policy and Research 18(3) 269–281.CrossRefGoogle Scholar
  44. United Nations Office on Drugs and Crime (UNODC) (2008) (2nd edition) UNODC Toolkit to combat trafficking in persons. Available Accessed 1 October 2018.
  45. UNODC (2009) Model law against trafficking in persons. Available Accessed 17 May 2018.
  46. United States Department of Justice (2018) Office for Victims of Crime and US Department of Justice Human Trafficking Task Force E-guide. Available Accessed 9 Oct 2018.
  47. United States Department of Justice (2017) National strategy to combat human trafficking. Available Accessed 1 Jun 2018.
  48. Winterdyk J (2017) Combating human trafficking at the local Level: Better informing (inter)national action plans. International Annals of Criminology 55: 220–236.CrossRefGoogle Scholar

Copyright information

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.University of ManchesterManchesterUK
  2. 2.Trilateral Research LtdLondonUK

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