The modern slavery defence: section 45 and the National Referral Mechanism
Victims of slavery or trafficking have a defence to most offences under Modern Slavery Act 2015 s.45, but not to the serious offences listed in Schedule 4. Drug supply and theft are not excluded, and once the defence is raised the prosecution must disprove it beyond reasonable doubt.
The defence
Section 45 of the Modern Slavery Act 2015 is a complete defence for victims of slavery or trafficking. It covers most offences, from 31 July 2015.
- Adults have the defence if all of these apply:
- they acted because they were compelled;
- the compulsion came from slavery or trafficking-related exploitation;
- a reasonable person in their situation, with their age, sex and any illness or disability, would have had no realistic alternative.
- Under-18s need no compulsion. The act must be a direct consequence of being a victim, and a reasonable person in their situation would have done it (s.45(4)). This test is less onerous (R v ADG [2023] EWCA Crim 1309).
Excluded offences (Schedule 4)
The excluded offences include murder, manslaughter, kidnapping, false imprisonment, perverting the course of justice, threats to kill, wounding or GBH (Offences Against the Person Act 1861 ss.18, 20), robbery, blackmail, arson, serious firearms offences, violent disorder, most sexual offences, terrorism and trafficking offences. Drug supply, cultivation, theft, actual bodily harm, knife possession and fraud are not excluded. This matters in county lines cases (see Drug offences: possession, intent to supply and supply).
Burden of proof
The defendant only has to raise the defence with evidence. The prosecution must then disprove it beyond reasonable doubt (R v MK and Gega [2018] EWCA Crim 667). If age is disputed, the prosecution must prove the defendant was 18 or over.
The National Referral Mechanism
- A first responder, such as the police or a local authority, refers the person to the Home Office. Adults must consent; children do not.
- A reasonable grounds decision should follow within 5 working days where possible. It brings a recovery period of at least 30 days before a conclusive grounds decision.
- Since 30 January 2023, a person can be disqualified from protection on public order grounds or for bad faith (Nationality and Borders Act 2022 s.63). Further restrictions in the Illegal Migration Act 2023 are not in force.
- A Home Office decision is not binding on the prosecution and is not admissible as evidence at trial (R v Brecani [2021] EWCA Crim 731).
The duty to consider prosecution
The CPS uses a four-stage test:
- Is there reason to believe the suspect is a victim?
- Is there clear evidence of duress?
- Is there clear evidence of the s.45 defence?
- Is prosecution still in the public interest?
Prosecutors must record clear reasons if they prosecute despite a positive conclusive grounds decision (VCL and AN v UK (2021) 73 EHRR 9). A court can stay an unfair prosecution as an abuse of process (R v L [2013] EWCA Crim 991).
In practice
Signs of exploitation should be raised early, ideally before charge, so a referral can be made. For under-18s, see Children and young people in the criminal justice system. Early advice matters.
Read the full guide on theodorous.uk
Authorities: Modern Slavery Act 2015 ss.45, 49, 52 and Sch.4 (as amended to 29 September 2026); Nationality and Borders Act 2022 s.63 (in force 30 January 2023); Illegal Migration Act 2023 ss.22-28 (repealed 2 December 2025 by Border Security, Asylum and Immigration Act 2025 s.41(1)(d)) and s.29 (not in force); R v L and others [2013] EWCA Crim 991; R v MK and Gega [2018] EWCA Crim 667; R v Brecani [2021] EWCA Crim 731; R v CS and Le [2021] EWCA Crim 134; R v ADG [2023] EWCA Crim 1309; VCL and AN v United Kingdom (2021) 73 EHRR 9; CPS prosecution guidance, Modern slavery and human trafficking: offences and defences, including the section 45 defence; Home Office, Modern slavery statutory guidance for England and Wales v4.9 (3 November 2026)