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Prosecutions under the Modern Slavery Act

Dr Alicia Heys is leading a workstream for the Human Rights and Modern Slavery Policy and Evidence Centre on the legal enforcement of modern slavery. Within this, she is beginning a project which will investigate the low prosecution and conviction rates under the Modern Slavery Act.

Dr Alicia Heys
Dr Alicia Heys, Lecturer in Modern Slavery Wilberforce Institute, University of Hull

Prosecution and conviction rates relating to modern slavery in the UK are low. The Court Proceedings Database shows that in 2017, 2018 and 2019 collectively, 64 adult offenders were sentenced for modern slavery and human trafficking offences under the Modern Slavery Act. In this same time frame, 22,756 potential victims of modern slavery were referred into the National Referral Mechanism (NRM), the UK’s system for identifying and supporting victims of modern slavery.

The gap between referrals and convictions shows little sign of closing. In 2020, the National Crime Agency estimated there to be at least 6,000-8,000 offenders involved in modern slavery that year. Yet in 2020, there were just 91 prosecutions and 56 convictions for modern slavery offenders (Centre for Social Justice, 2022).

The UK’s Modern Slavery Act was introduced in 2015 with the plan to ‘give law enforcement the tools to fight modern slavery, ensure perpetrators can receive suitably severe punishments for these appalling crimes and enhance support and protection for victims’ (Home Office, 2014).  However, further data shows that the mean custodial length for adult offenders sentenced between 2017 and 2019 under section 1 of the Modern Slavery Act (slavery, servitude, forced or compulsory labour) was 5.4 years and under section 2 (human trafficking) was 5.6 years. These figures of prosecutions, convictions and sentence lengths suggest that the Modern Slavery Act is yet to meet its goal in ensuring that offenders are held to justice with suitably severe punishments.

A image of a court gavel

My research project will investigate why the rates are so low, and assess the feasibility of using financial investigations as a method of identifying victims and perpetrators, leading to prosecutions and seizing assets.

There is a level of understanding amongst practitioners and policymakers regarding barriers to a successful prosecution under the Modern Slavery Act, especially where these prosecutions rely heavily on victim testimony. It can be hugely challenging for victims to be involved in the criminal justice process that seeks to prosecute their perpetrator. Some may simply be too fearful to want to provide evidence against their perpetrator. While victims of modern slavery are afforded special measures in court which may include screens to shield witnesses from defendants, giving evidence via video, or reporting restrictions, some may be too afraid of the perpetrator and the potential consequences not only for themselves (Cooper et al., 2017), but for their family or friends (Pascual-Leone et al., 2017) to wish to give evidence.

Others may be afraid of authorities, especially if they have a precarious immigration status or if they have been victimised into criminal exploitation and thus coerced into committing criminal acts. In such situations, the victims may be reluctant to come forward for fear of detention, deportation or arrest (ILO, 2005; Centre for Social Justice, 2021; Schwarz and Williams-Woods, 2022).

This research project will consider these and other reasons why victims may be reluctant to engage in the criminal justice process, but it will also build upon a report from the Independent Anti-Slavery Commissioner’s office which indicated that financial investigations could offer an alternative route to identifying perpetrators. This will involve interviewing police officers, lawyers and financial investigators to gather insights into how financial investigations could be used to lead to prosecutions. By generating an understanding of how financial investigations into criminal activity are currently undertaken, and identifying specific indicators that could be illustrative of modern slavery offences, we will be able to assess how feasible it could be to use financial investigations as a method to secure prosecutions without having to rely on victim testimony.

I will be collecting this data until July 2023 and will be writing the findings into a publicly-accessible report which will be published at the end of the project.


Centre for Social Justice (2022) A Path to Freedom and Justice: a new vision for supporting victims of modern slavery.

Cooper, C., Hesketh, O., Ellis, N., Fair, A. (2017) A Typology of Modern Slavery Offences in the UK: Research Report 93. Home Office.

Home Office (2014) Modern Slavery Act 2015.

International Labour Organization (2005) A Global Alliance Against Forced Labour. Geneva: International Labour Office.

Pascual-Leone, A., Kim, J., Morrison, O. (2017) Working with Victims of Human Trafficking. Journal of Contemporary Psychotherapy 47: 51-59.

Schwarz, K., and Williams-Woods, A. (2022) Protection and Support for Survivors of Modern Slavery in the UK: Assessing Current Provision and What We Need to Change. Journal of Poverty and Social Justice 30(2): 98-119.

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