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Explainer: Modern slavery clauses in Illegal Migration Bill

Explainer of the modern slavery clauses in the Illegal Migration Bill and legal analysis of its compatibility with international legislation.

Published: 28th March 2023

On 7 March 2023, the UK Government introduced the Illegal Migration Bill with the stated purpose to “prevent and deter unlawful migration, and in particular migration by unsafe and illegal routes.” The Bill introduces provisions that would amend immigration, asylum, and modern slavery legislation.

This Explainer aims to answer common questions about the modern slavery provisions in the Bill. It is based on a rapid assessment of what is known from research, evidence and data about the rationale for the modern slavery provisions and their potential implications and a legal analysis of the human rights compatibility of the Bill’s modern slavery provisions. This Explainer was produced by the Modern Slavery PEC’s policy impact team, alongside the PEC’s lived experience engagement team.

The legal analysis commissioned by the Modern Slavery PEC was undertaken by Dr Marija Jovanovic from the University of Essex, which we publish below.

This Explainer will be updated as the Bill progresses through Parliament and new evidence becomes available.

The latest version has been published on 2 June 2023.

Please see below for the specific updates made to the Explainer:

1. Updates made to section on the rationale and policy objectives of the Bill, to align with updates made to Home Office Illegal Migration Bill 'factsheets' on 11 May 2023.

2. Inserted reference to the Equality Impact Assessment of the Bill, published 11 May 2023.

3. Expanded the paragraph relating to the reasonable grounds decision rate for Q1 2023.

4. Minor edits for clarity made, alongside minor formatting changes.

You can also read a short fact sheet on modern slavery in relation to the Bill


  • The Illegal Migration Bill, if enacted, would have serious implications for large numbers of people who are victims of modern slavery. It provides for the denial of support, and for the detention and deportation of people who are recognised to be potential victims of modern slavery.
  • Thousands of potential victims of modern slavery may be denied protections by the modern slavery provisions in the Bill. This will include people for whom their entry to the UK is an integral element of the criminal offence of trafficking committed against them (see paragraphs 5-6).
  • The need for these provisions is predicated on the UK Government’s assumption that people are ‘abusing’ the modern slavery system, and that the system is an incentive for illegal migration to the UK. The available evidence questions both of these assumptions (see paragraphs 3-4; 7-13).
  • The modern slavery measures in the Bill are incompatible with the UK’s obligations under Article 4 of the European Convention on Human Rights (ECHR), which are part of UK law under the Human Rights Act 1998 (HRA), and its obligations in international law under the European Convention Against Trafficking (ECAT) (see paragraphs 15-19).
  • Under the modern slavery provisions, potential victims may be denied protection and support and removed from the UK before the victim identification process has been completed, impacting on their safety from traffickers and their recovery from exploitation. While there are exceptions for those supporting investigations and prosecutions, a Government amendment to the Bill (made in April 2023) creates a presumption that survivors’ presence in the UK is not required to provide this support, unless the Home Secretary determines there are compelling circumstances. This is very likely to reduce survivors’ willingness and ability to cooperate with authorities in criminal proceedings, which often plays a central role in successful prosecutions (see paragraphs 20-22).
  • The measures that are not specific to modern slavery may directly harm people affected by modern slavery who seek asylum or humanitarian protection by increasing their susceptibility to exploitation and trafficking, and by exposing them to long-term psychological harm through, for example, detention (see paragraphs 23-24).

The earlier versions of the Explainer: