The considerable harms of human trafficking, modern slavery and commercial sexual exploitation are widely recognised, and this area of offending and victim vulnerability has thus become a priority for the vast majority of policing and criminal justice agencies across the world (see HM Government 2023, and others). Although human trafficking and modern slavery are not new phenomena, over the past decade such activities have undergone a significant surge due to the continued development and proliferation of digital technologies and networked environments (Europol 2016). Governments and law enforcement agencies have in recent years emphasized the immense difficulties of tackling modern slavery and human trafficking in the context of evolving online platforms and the affordances of digital technologies to ‘bad actors’ (HM Government 2023; Europol 2016; Council of Europe 2022; OSCE, 2023). On one hand, new technological opportunities – whether in the form of devices, platforms, or even specific features within websites – enable traffickers to continuously adapt and attempt to elude law enforcement. On the other, alongside a recognition of these difficulties, there is a growing consensus among researchers and practitioners that the traffickers’ very use of technology can leave important traces through which they may be apprehended through law enforcement innovation and collaboration with partner agencies and non-governmental organisations (see L’Hoiry et al., this issue; Giommoni and Ikwu, this issue; OSCE, 2020). This special issue contributes to these developments and knowledge base by bringing together four articles that focus on the use of online platforms by human traffickers for the purposes of commercial sexual exploitation. In doing so, this special issue explores the affordances of online platforms to human traffickers, the challenges faced by law enforcement and other actors seeking to intervene in human trafficking in the digital age, and perhaps pathways towards overcoming these challenges in the future.

Contemporary human trafficking processes that are embedded in the use and exploitation of digital technologies undoubtedly present a new and considerable challenge (Antonopoulos et al. 2020). A Council of Europe (2022) study engaging with law enforcement practitioners, NGOs and tech companies across Europe has previously identified digital technologies as impacting and, in some ways, ‘reinventing’ human trafficking processes, particularly in the context of recruitment, exploitation and control. With regards to recruitment for the purposes of sexual exploitation, as an example, online platforms appear to have allowed for the apparent reinvention of the so-called ‘lover boy method’ in a digital context. This commonly cited and almost stereotypical form of recruitment by human traffickers involves (usually) male offenders deceiving (usually) female individuals into entering romantic relationships, before abusing such relationships to exploit and control victims. Despite previous work questioning how prolific this type of recruitment activity is in practice as opposed to media-induced moral panics (Bovenkerk and van San 2011), the use of digital platforms is said to have afforded new opportunities for offenders to approach potential victims via dating apps, social media and other online media. Through such new means, the same strategy of building rapport and trust that is designed to eventually exploit and control victims can be employed. Linked to this, the use of online platforms such as social media and messaging apps to gather potentially compromising material from victims, such as nude pictures, has also been identified as a method of recruitment of victims to ‘coerce them into prostitution’ (Council of Europe 2022: 12). Practices of exploitation and control have also been granted new affordances thanks to emerging digital technologies. New and continuously growing online spaces allow traffickers to advertise the forced sexual services of their victims via adult service websites or social media platforms (this is discussed in greater detail below).

Among the key changes brought about by the increased use of digital technologies during processes of human trafficking is the way in which space and physical proximity manifests in this context. The new dimension of space in contemporary human trafficking processes taking place via online platforms allows traffickers to recruit, control and exploit victims without necessarily meeting them in person (Antonopoulos et al. 2020; Council of Europe 2022). Physical proximity is therefore becoming less relevant in digital spaces, with research identifying examples of victims in one country being exploited and controlled by traffickers in another (Antonopoulos et al. 2020; OSCE, 2023; Council of Europe 2022). The use of the internet in this context and the transcendence of in-person interactions have also enabled traffickers to reach a much wider customer base than street-based sexual exploitation would have previously allowed. This undoubtedly presents new challenges for the detection and investigation of such cases given the dispersal of the actors involved. Traditional law enforcement investigatory practices may not be appropriate to adapt to the difficulties resulting from the physical separation between offenders and victims, although this is certainly not the only challenge to law enforcement interventions in this context. Other barriers to detection, investigation and prosecution have been identified as including the sheer volume of digital data to be investigated (and the resources necessary to carry this out); the obfuscation of identifiable details online (e.g.: use of nicknames; use of VPNs; encrypted communications) meaning identifying offenders and victims becomes exceptionally difficult; the ability to rapidly change offender behaviours and modus operandi online to avoid law enforcement detection (e.g.: using different communication platforms; using translation services to change language); and the lack of specialist units, technical equipment and training within law enforcement and other criminal justice agencies to effectively respond and rapidly adapt to new forms of offending mediated online. The impacts of digital technologies on human trafficking and law enforcement responses to this rapidly changing landscape are therefore not inconsiderable.

Adult service websites and commercial sexual exploitation

The challenges of combatting human trafficking in a digital age are arguably most demonstratable in the apparent use of Adult Service Websites (ASWs) by human traffickers; considerable space is, therefore, devoted to exploring these online platforms in the present special issue. ASWs allow users to advertise their sexual services by creating profiles where they can upload photos, provide contact details, and outline the services they are willing to provide and their cost. These online platforms have fundamentally altered the marketplace for sex by creating a virtual red-light district (Perer 2012) connecting supply and demand in an online environment at relatively low risk of law enforcement intervention. ASWs are commonly used by non-trafficked sex workers, and some have argued that ASWs offer sex workers a safer environment in which to operate and a welcome retreat from the risks of street-based sex work, such as violence and other harmful experiences (Blunt and Wolf 2020). In recent years, however, traffickers have made increased use of ASWs to post profiles advertising the forced sexual labour of their victims, falsely portraying them as consenting. This camouflaging of victims among non-trafficked sex workers has allowed offenders to, as mentioned above, considerably expand their reach using online advertising as compared to street-based activities. Such is the scale of this problem that in 2018, the Joint Slavery and Trafficking Analysis Centre in the UK stated that ASWs represent ‘the most significant enabler of sexual exploitation in the UK’ (APPG, 2018). A recent OSCE report described the use of ASWs as central to human traffickers’ sexual exploitation processes, serving ‘as a primary venue for commercial sexual exploitation and trafficking’ (OSCE, 2023: 10). By way of example, the report quotes from previous research by the NGO Thorn which found that of 260 survivors of sexual exploitation, 80% reported having had their forced sexual services advertised online. The OSCE (2023) has also been keen to emphasize that the challenge of human traffickers’ use of ASWs is not limited to countries such as the US or the UK but is instead an issue experienced across the world and certainly across the 40 countries spanning three continents, which formed the basis of their study.

The growing recognition that ASWs are used by human traffickers in the course of their exploitative activities has led to such platforms receiving increased academic, law enforcement and policymaking attention. Academic studies into ASWs and their links to human trafficking emerged over a decade ago thanks to works such as those by Latonero (2011), Latonero et al. (2012), Ibanez and Suthers (2014), Ibanez and Gazan (2016) and Alvari et al. (2017) in the US, and Diba et al. (2017) and Skidmore et al. (2018) in the UK. Governmental attention in this context is more recent. In 2018, the US government passed the Stop Enabling Sex Traffickers Act (SESTA) and Allow States and Victims to Fight Online Sex Trafficking Act (FOSTA), commonly known as SESTA-FOSTA. These acts were ostensibly aimed at tackling human trafficking mediated via online platforms such as ASWs. Perhaps unsurprisingly, the shutdown of ASWs, including the market-leading Backpage.com (which in fact preceded the passing of SESTA-FOSTA) in the US has received mixed responses. Some, such as the National Centre for Missing and Exploited Children, have celebrated this move as a positive step forward and a key deterrent for human traffickers and ASW operators deliberately hosting (and profiting from) ads created by human traffickers on their platforms (Robertson 2021). Sex work advocate groups and others, however, have strongly criticised this move, arguing that ‘rather than preventing the online exploitation of trafficked persons, these laws have hurt the people they intended to help, pushing sex workers and trafficking victims into more dangerous and exploitative situations’ (Decriminalize Sex Work 2023). Specifically, it is argued that the criminalisation of ASWs has removed ‘communication and safety networks for sex workers and other at-risk communities’ as well as hindering law enforcement efforts to combat human trafficking by removing a key source of digital intelligence. Research has found that in the aftermath of SESTA-FOSTA, sex workers reported feeling less safe and more financially vulnerable as a result of the lost income previously generated via advertising on ASWs (Blunt and Wolf 2020). Such adverse impacts on non-trafficked sex workers have led some commentators to describe SESTA-FOSTA as having ‘failed miserably’ (Grant 2021), not least because a governmental report in 2021 conceded that the law had, three years after its introduction, been rarely used by prosecutors in the US (US Government Accountability Office 2021).

In the UK, enquiries conducted by both Westminster and the Scottish Parliament have painted a damning picture of ASWs, echoing US narratives in routinely describing such platforms as ‘pimping sites’ (All Party Parliamentary Group on Commercial Sexual Exploitation, 2021: 4; Cross-Party Group on Commercial Sexual Exploitation 2021). The use of ASWs is identified in governmental reports as ‘the most common model of operation used by organised crime groups engaged in sexual exploitation’ and as ‘key to the typical business model used by sex traffickers in the UK’ (APPG on CSE, 2021: 17). ASWs are understood as shaping and driving the demand for sex, which in turn creates further technological opportunities and financial incentives for human traffickers to increase the exploitation of their victims. These parliamentary enquiries have proposed that the affordances of ASWs make it ‘quick and easy for traffickers and pimps to connect with sex buyers across the country’ (APPG on CSE, 2021: 17). Such is the apparent scale of this issue that the UK has been described as a ‘pimp’s paradise’ (Weaver 2020) and British police forces seeking to work with ASWs to identify suspect cases have been accused of ‘cosying up and enabling’ (Syal 2023) ASWs to facilitate the exploitation of vulnerable people. The culmination of these enquiries has seen recommendations to criminalise ASWs in the UK, apparently seeking to follow the US approach in this regard. UK lawmakers do not therefore appear to be heeding the concerns raised in the US in the years following SESTA-FOSTA, with several of these concerns described as ‘myths and misinformation’ (APPG on CSE, 2021: 18). It should further be noted that, alongside these debates, there are academic and non-academic outputs which have contested the extent to which ASWs are used by human traffickers (see Martin and Hill 2019). These contributions have also raised questions as to the role of third parties who may support (particularly migrant) sex workers by creating and maintaining ASW profiles, but in doing so have also been accused of exploiting victims (Broad and Gadd 2022).

It is within this challenging, fast-moving and contested landscape that the articles in this special issue on human trafficking, sexual exploitation and digital technologies seek to develop academic knowledge and inform practice and policy in this important context.

Articles in this special issue

This special issue features four articles exploring adult service websites (ASWs), reflecting perhaps the increased academic attention these online platforms have been receiving from scholars with interests in human trafficking and sexual exploitation. Firstly, Giommoni and Ikwu’s article presents a quantitative analysis of risk indicators appearing in an ASW operating in the UK. Having developed a scraping and crawling software, the authors deploy a robust and replicable methodology to analyse over 17,000 adverts on the UK’s market-leading ASW, applying 10 risk indicators (drawn from United Nations Office on Drugs and Crime 2020) to assess the frequency at which these indicators appear across their sample. In doing so, the article builds on existing attempts to analyse large volume of ASW data in order to identify the repeated posting behaviours of traffickers using these platforms to imitate the profiles of non-trafficked sex workers. Giommoni and Ikwu’s article is one of the few to do so in the UK, with the majority of such research taking place in the US (see Ibanez and Suthers 2014; Ibanez and Gazan 2016; Alvari et al. 2017). It is worth noting that the article helpfully sounds a note of caution regarding over-reliance on risk indicators when assessing ASW profiles and, indeed, the inherent potential for risk analyses of this type to produce false positive and negatives when attempting to distinguish sex workers from potential victims of human trafficking and sexual exploitation.

The second article by L’Hoiry, Moretti and Antonopoulos presents a case study conducted with a British police force during which a risk assessment and decision support tool, the Sexual Trafficking Identification Matrix (STIM), was created and tested in a live operational environment. As the article details, the STIM was created to support users to (a) more accurately distinguish potentially false ASW profiles from those posted by non-trafficked sex workers and (b) risk assess the profiles identified/flagged as problematic in order to prioritise those requiring immediate action, given the important financial context of limited law enforcement resources. Building on previous attempts to collate risk indicators appearing in ASW adverts (see Ibanez and Suthers 2014; Ibanez and Gazan 2016; Alvari et al. 2017), the STIM lists a series of objective and subjective risk indicators appearing in any given ASW profile ultimately seeking to significantly develop police investigatory practices in this context. As the authors explain, the risk indicators contained within the STIM represent the synthesis of various data including a systematic literature review as well as a series of interviews with multiple actors with interests in commercial sexual exploitation mediated online. The article also reflects on the process of co-producing the STIM and on academic attempts to collaborate with law enforcement practitioners to create tools that are evidence-based and have practical value for front-line practitioners.

In the third article in this special issue, Hopkins, Keighley and Sanders also focus on ASWs, but offer a novel perspective on existing discussions by using ASWs and the illicit entrepreneurial activities taking place on these online platforms to frame organised crime as an ecosystem involving multiple actors. In the context of human trafficking and commercial sexual exploitation facilitated by ASWs, the authors identify an ecosystem consisting of organisers/criminal networks, marketers/advertisers, the exploited, and buyers of sex. The analysis usefully highlights the challenges for law enforcement interventions in penetrating and disrupting such ecosystems, not least the affordances of digital platforms which enable human traffickers to maintain a distance from selling sex by mediating these activities through ASWs. Parallel to these discussions, the authors also reflect on recent political rhetoric and policy in the UK concerning irregular migration. They argue that the increasingly hostile nature of governmental action on this issue has offered organised crime groups an advantage in leveraging the fears and the ‘hyper-precarity’ (Lewis et al. 2015) of regular and irregular migrants that they will be detained and deported by authorities to exert greater control over them.

Finally, Huang, Yoder, Tsoukalas, Entress and Sadiq’s article tackles a question often explored in research concerning online advertisements of sexual services: is it possible to trace changes in online sex advertisements in response to significant and temporary social events? Previous research has explored whether such a link exists with mixed results (compare, for instance, Latonero 2011 & Martin and Hill 2019). Finkel and Finkel’s (2015) review of existing literature on this topic found limited evidence establishing a clear link between a series of significant sporting events (such as the 2004 Olympic Games and the 2006 World Cup) and corresponding increases in online sex advertisements. However, Finkel and Finklel (2015) conclude by calling for more research on this theme, given the hidden nature of commercial sexual exploitation. Huang et al. answer this call by considering two Super Bowl weekends taking place in 2020 and 2021 in two US cities, analysing changes on ASW platforms to determine whether the Super Bowl weekend could be linked to an increase in demand for and therefore a corresponding availability of illicit services such as sex. Using time series analysis to identify what they describe as ‘anomalies’ in online advertisements prior to and during these events, the authors present data indicating an increase in both adverts appearing to be posted by non-trafficked sex workers and adverts appearing to be posted by human traffickers during Super Bowl weekends in 2020 and 2021. These findings offer a valuable new addition to the contested landscape of research on this issue and invite further analyses of the link between sporting mega-events and trends in online sex advertising.

Common across all articles in this special issue is a recognition that constantly evolving digital technologies offer offenders a series of affordances which both facilitate criminal activities and obfuscate law enforcement efforts to intervene. ASWs are one of several examples of online platforms which appear to be increasingly used by human traffickers to exploit their victims and maximise their profits. As the Council of Europe (2022: 10) has previously stated, ‘technology is here to stay – and with it, structural changes in the way offenders operate, opportunities open up and existing vulnerabilities are exacerbated’. A key feature of all articles in this special issue is a desire to develop law enforcement and NGO practices in this area that can in some way keep up with the traffickers’ increasingly technological modi operandi, either by addressing knowledge gaps or by offering evidence-based tools to combat commercial sexual exploitation online.

Finally, and predictably, a common theme across all articles in this special issue is a call for greater empirical research, involving a range of methodological approaches. Several knowledge gaps are identified in the four articles, including a lack of engagement with key actors in the context of human trafficking, the exploiters and the exploited. While these may be considered hard to reach groups, meaningfully developing knowledge in this field nonetheless requires scholars to capture these important perspectives. The articles in this special issue concerned with the use of risk indicators to identify potential cases of human trafficking on ASWs also call for greater development of these indicators and how they may be created and deployed in ways which minimise the potential for false positives and negatives while retaining value for practitioners. Alongside this continued engagement with technology on the part of law enforcement and other practitioners, the reality that human traffickers are exploiting the same technological advances – and may, indeed, find themselves several steps ahead in what could be characterised as a ‘cat and mouse chase’ between organised criminals and enforcement agencies – remains a major concern. Closely linked to this are questions concerning the shutting down of ASWs, as has been done in the US and is presently being considered in the UK, and whether in fact such platforms could constitute valuable data sources for the ongoing fight against human trafficking in the digital age.

We would like to thank the contributors for their timely delivery of drafts, the reviewers for their valuable comments and constructive criticism, as well as Emily Balangatan and Arlie Cataylo from Springer for their assistance with production-related issues.