The tenth anniversary of the Modern Slavery Act 2015

Harriet Samuel

What is modern slavery?

The government has described modern slavery as a “brutal form of organised crime in which people are treated as commodities and exploited for criminal gain”, which “takes a number of forms, including sexual exploitation, forced labour and domestic servitude”.

Statutory Guidance issued by the Home Office outlines the definition of modern slavery. It highlights the following key points:

Modern slavery encompasses human trafficking and slavery, servitude and forced or compulsory labour.
Human trafficking consists of three basic components: action, means and purpose of exploitation. All three components must be present in an adult trafficking case; for child trafficking the ‘means’ component is not required.
In human trafficking cases, exploitation can take many forms, including sexual exploitation, forced labour, slavery, servitude, forced criminality and removal of organs.
Some people may not be victims of human trafficking but still victims of modern slavery if they have been subject to slavery, servitude and forced or compulsory labour.
Human trafficking is not the same as human smuggling. There are common myths about modern slavery, such as misconceptions that UK nationals cannot be victims and that a person cannot be a victim if they reject offers of help.

The guidance also notes that “the definition of a victim of human trafficking, slavery, servitude and forced or compulsory labour is set out in the Slavery and Human Trafficking (Definition of Victim) Regulations 2022”.

According to the Home Office’s National Referral Mechanism guidance, for a person to have been a victim of slavery, servitude and forced or compulsory labour there must have been:

means (being held, either physically or through threat of penalty – for example, threat or use of force, coercion, abduction, fraud, deception, abuse of power or vulnerability. However, there does not need to be a means used for children as they are not able to give informed consent)
service (an individual provides a service for benefit – for example, begging, sexual services, manual labour, domestic service)

The government has identified 17 types of modern slavery (PDF) which fall into four categories – labour exploitation, domestic servitude, sexual exploitation, and criminal exploitation

Some people may not be victims of human trafficking but still be victims of modern slavery.

The prevalence of modern slavery

The Home Office says that the true extent of modern slavery is difficult to ascertain, as it is a “highly complex and hidden crime”(PDF).

According to the Office for National Statistics (ONS): “The hidden nature of modern slavery makes producing an accurate prevalence measure difficult”. Therefore, there is no one data source that accurately quantifies the number of victims in the UK. Data for the UK National Referral Mechanism (NRM) is given below. The NRM is the UK’s framework for identifying potential victims of modern slavery and ensuring they can access support. The ONS said that this is the “best measure of potential victims, although [it] is known to be an undercount”.

Since the Modern Slavery Act was introduced in 2015, the number of referrals have increased by 486%, from 3,261 referrals in 2016 (PDF) to 19,125 in 2024.

According to the Home Office’s 2024 statistics on referrals to the NRM, there were 19,125 potential victims of modern slavery who were referred to the Home Office in 2024. This is a 13% increase from 2023 (16,990 referrals), and the highest number of referrals on record. Of this:

13,100 were potential victims who claimed exploitation as adults (68%)
- 9,459 were male (72%)
- 3,626 were female (28%)
5,999 were children (31%)
- 4,677 were male (78%)
- 1,306 were female (22%)

Adult victims were most commonly referred for labour exploitation (41%); for children, criminal exploitation was the most common (48%). It is also worth noting that exploitation types tend to have gendered patterns, with female victims most often reporting sexual exploitation (31%), and male victims most often reporting labour exploitation (39%).

362 nationalities were represented by referrals in 2024. The most common nationality was UK (23% of those referred), followed by Albanian (13% of referrals), and Vietnamese (11% of referrals).

Modern Slavery Act 2015

The Modern Slavery Act 2015 received royal assent on 26 March 2015. The Act applies to England and Wales. In the same year, the Human Trafficking and Exploitation (Scotland) Act 2015 and the Human Trafficking and Exploitation (Criminal Justice and Support for Victims) Act (Northern Ireland) 2015 were passed in Scotland and Northern Ireland, respectively.

The Home Office provides the following overview of the Act’s provisions:

consolidate and simplify existing offences into a single act
ensure that perpetrators receive suitably severe punishments for modern slavery crimes (including life sentences)
enhance the court’s ability to put restrictions on individuals where it’s necessary to protect people from the harm caused by modern slavery offences
create an independent anti-slavery commissioner to improve and better coordinate the response to modern slavery
introduce a defence for victims of slavery and trafficking
place a duty on the secretary of state to produce statutory guidance on victim identification and victim services
enable the secretary of state to make regulations relating to the identification of and support for victims
make provision for (now referred to as Independent Child Trafficking Guardians (ICTGs))
introduce a new reparation order to encourage the courts to compensate victims where assets are confiscated from perpetrators
enable law enforcement to stop boats where slaves are suspected of being held or trafficked
require businesses over a certain size to disclose each year what action they have taken to ensure there is no modern slavery in their business or supply chains (further information on how this obligation should be fulfilled is available in Transparency in supply chains: A practical guide)

Together with part 5 of the Nationality and Borders Act 2022, these Acts make up the UK’s domestic modern slavery legislation. The provisions in the Nationality and Boarders Act 2022 are intended to facilitate early identification of victims and deter misuse of the National Referral Mechanism.

Statutory guidance

Section 49 of the Modern Slavery Act 2015 requires the Secretary of State to issue guidance about identifying and supporting victims. For instance, the indicators of modern slavery, and arrangements for providing support. This is published as Modern Slavery: statutory guidance for England and Wales (under s49 of the Modern Slavery Act 2015) and non-statutory guidance for Scotland and Northern Ireland.

Independent Anti-Slavery Commissioner

Section 40 of the Act requires the Secretary of State to appoint an Independent Anti-Slavery Commissioner (IASC). The role of the Independent Anti-Slavery Commissioner is to “‘encourage good practice sharing’ amongst all those with a role to play in tacking every aspect of modern slavery and human trafficking in the UK”. The Commissioner is accountable through their Strategic Plan and annual reports, which must be laid before Parliament by the Home Secretary. The current IASC is Eleanor Lyons.

National Referral Mechanism

As previously mentioned, the National Referral Mechanism (NRM) is a “UK-wide framework for identifying and referring potential victims of modern slavery and ensuring they receive the appropriate support”.

First Responder Organisations

Individuals cannot apply to be recognised as possible victims of modern slavery. Only First Responder Organisations are authorised to refer someone into the NRM.

Section 52 of the Modern Slavery Act 2015 creates a statutory duty for specified public authorities in England and Wales to notify the Home Office about suspected victims of modern slavery.

The current statutory and non-statutory First Responder Organisations in England and Wales includes charities and government bodies. There are different cohorts of First Responder Organisations in Scotland and Northern Ireland. The Statutory Guidance states that First Responder Organisations have four primary responsibilities:

Identify potential victims of modern slavery and recognise the indicators of modern slavery
Gather information in order to understand what has happened to them
Refer victims into the NRM via the online process (in England and Wales this includes notifying the Home Office if an adult victim doesn’t consent to being referred – this is referred to as a Duty to Notify)
Provide a point of contact for the competent authority to assist with the Reasonable and Conclusive Grounds decisions and to request a reconsideration where a first responder believes it is appropriate to do so

NRM referrals must be made for any person under the age of 18. Consent is required for an adult to be referred to the NRM. For an adult to provide their informed consent, a first responder must explain: what the NRM is; what support is available through it; what the possible outcomes are for an individual being referred.

Decision-making authorities

Decisions as to whether an individual is a victim are made by one of two ‘competent authorities’: the Immigration Enforcement Competent Authority (IECA) and the Single Competent Authority (SCA).

The decision is split over two parts: reasonable grounds and conclusive grounds. Section 7 of the statutory guidance states the following regarding the two stages of decision-making:

Following referral from a First Responder Organisation, the relevant competent authority will make a Reasonable Grounds decision to determine whether an individual is a potential victim of modern slavery. This decision should be made within 5 working days of referral, where possible. Following a positive Reasonable Grounds decision, a potential victim will receive a Recovery Period of at least 30 calendar days and will be able to receive support as set out in the Support section.
The relevant competent authority will make a Conclusive Grounds decision at least 30 calendar days after the reasonable grounds decision, to determine whether ‘on the balance of probabilities’ there are sufficient grounds to decide that the individual is a victim of modern slavery. In many cases a decision will take longer, as all relevant information must be shared and made available to the relevant competent authority to inform the decision, which can often take interested parties significant time to provide. Following a positive Conclusive Grounds decision, victims will be exited from support only when appropriate to do so. Victims with a positive Conclusive Grounds decision will receive at least 45 calendar days of support during the move-on support period.

Support for victims

Support for potential victims may include accommodation, independent emotional and practical help, and access to relevant legal advice. The period for which this support will be available and the organisation that delivers it is dependent on which part of the UK the individual is in.

Reviews of the Act

Home Affairs Committee ten year review (2025)

The Home Affairs Committee examined the impact of the Modern Slavery Act in an evidence session on 25 March 2025. A recording of the session and the oral evidence transcripts are available to view online.

The session saw oral evidence given by Major Kathy Betteridge (the Director for Anti-Trafficking and Modern Slavery at the Salvation Army), Emma Hawley (Assistant Director at Independent Child Trafficking Guardian Services), Caroline Haughey KC, Eleanor Lyons (Independent Anti-Slavery Commissioner), and Baroness Butler-Sloss.

House of Lords post-legislative scrutiny review (2024)

On 24 January 2024, the House of Lords appointed a committee to conduct a post-legislative review of the Modern Slavery Act 2015. The committee inquiry focused on:

the impact of immigration legislation
the care sector as a case study of labour exploitation to demonstrate the practical impact of the Act
enforcement of and prosecutions under the Act
supply chains
the IASC

On 16 October 2024, the committee published its report: ‘The Modern Slavery Act 2015: becoming world-leading again’ (PDF).

The report stated that while it was world-leading at the time it was passed in 2015, the Act can no-longer be considered as “the world has changed and best practice has moved on”.

The key findings of the report were:

The Nationality and Boarders Act 2022, Illegal Migration Act 2023, and the Safety of Rwanda (Asylum and Immigration) Act 2024 limit the access victims have to support: “Recent immigration legislation has limited the support which the Act originally afforded to victims. This has left victims vulnerable, without adequate protection from their traffickers. The new government should recognise the difference between willing migrants and those forced to come to the UK, and develop policy accordingly. Some of the legislative changes that have been passed should be reversed, or left uncommenced, and the safeguarding of victims must be prioritised.”
Since the Act was introduced, the care sector has become focal point for modern slavery and labour exploitation, with large increases in victims in the sector: “There has been a substantial recent increase in reported victims in the care sector, many of whom are charged exorbitant recruitment fees and subjected to working conditions that flout the law. This has resulted from the relaxation of visa rules without there being appropriate regulation of employers in place. The Government should ensure workers have decent rights and provide the resources to enforce these, including through the creation of a Single Enforcement Body.”
The Slavery and Trafficking Risk Orders (STROs) and Slavery and Trafficking Prevention Orders (STPOs) provided by the Act are underutilised, leading to a very small number of prosecutions under the Act: “The proportion of prosecutions to National Referral Mechanism referrals is only 1.8%, despite the focus which the Act paid to enforcement. This means perpetrators are free to profit from victims without feeling at substantial risk of repercussions. Since modern slavery is a hidden crime, investigations are complex, but there are known ways of improving their success. The Government should facilitate better use of the Orders introduced by the Act, improve evidence gathering, and develop a sharper strategic approach.”
The lack of a mandated requirement for content in modern slavery statements means that the statements from companies are inconsistent and does not hold them accountable. The supply chain requirements of the Act are not enforced to the extent they should be to make an impact: “The Act introduced a requirement for companies to report on how they tackle modern slavery in their supply chains. This has great potential but current legislation is too limited to have significant practical impact. Publication of statements should be widened and compliance with requirements should be enforced, both for companies and public bodies. There should be progression towards international best practice concerning due diligence and import bans on companies producing services and goods made with forced labour”.
There were issues around appointing, providing a sufficient budget for, and ensuring government engagement across all departments with the Independent Anti-Slavery Commissioner: “The Act created the office of the Independent Anti-Slavery Commissioner to provide impartial oversight of Government policy in this area. The recent vacancy of the post for eighteen months sent a message that the previous Government had deprioritised this work. The Commissioner’s independence should be ensured both by the appointment process and the provision of adequate resources”.

Government response to the report

The government published its response to the committee’s report on 16 December 2024.

In the response, the government stated a “renewed commitment to joint working between Government, law enforcement and criminal justice system partners and civil society”, to work towards a “holistic victim centred approach” to preventing and addressing modern slavery. The response stated that:

Long-term reform of the modern slavery approach will focus on driving up prosecutions and convictions and ensuring tailored and holistic support is available for victims, providing them with access to the help they need to rebuild their lives.

In the response, the government said that many of the committee’s recommendations had been accepted (such as ending the migration partnership with Rwanda, looking to strengthen STROs and STPOs, and making modern slavery transparency data publicly available through a data dashboard), and many will be “fully considered” in the development of future policies.

The response also noted measures that had already been put in place by the new government, such as the commitment to introduce a standalone offence of child criminal exploitation and the creation of the Fair Work Agency through the Employment Rights Bill.

Further details of the government’s response to the report, as well as responses to individual committee recommendations can be found in the full report response.

Independent review of the Modern Slavery Act (2019)

On 30 July 2018, the Home Office announced plans to launch an independent review of the Modern Slavery Act, to be conducted by Frank Field MP, Maria Miller MP, and Baroness Butler-Sloss.

The review was established to look into the operation and effectiveness of the Act and suggest potential improvements. It focused on four areas:

The Independent Anti-Slavery Commissioner
Transparency in supply chains
Independent Child Trafficking Advocates (an “independent source of advice for children who have been trafficked and somebody who can speak up on their behalf”.)
The legal application of the Act, including:
- The definition of exploitation
- Reparation orders
- The statutory defence

The final report of the Review was published in May 2019 (PDF). It summarised the interim reports and provided a list of 80 recommendations, as well as commenting on some other issues identified in the course of the Review. These recommendations included:

emphasising the independence of the Commissioner role
strengthening statutory guidance on transparency in supply chains
the need for policy guidance to help with the interpretation of the Act
recommended amendments to the Act to clearly show that a child is not able to consent to any element of their trafficking.

The government published its response to the review (PDF) on 9 July 2019, in which it accepted the majority of the Review’s recommendations.

Modern Slavery Act 2015 review: one year on (2016)

As Home Secretary, Theresa May set up an independent review of the 2015 Act a year after it came into force. The review, by barrister Caroline Haughey QC, found that it had set “an international benchmark to which other jurisdictions aspire”. It found that slavery remained under-reported, but the operational response was improving.

However, the review said there were problems, including a lack of consistency between law enforcement and criminal justice agencies and poor-quality intelligence at all levels. The review recommended better training and a more structured approach to prosecuting and preventing slavery.

The tenth anniversary of the Modern Slavery Act 2015

What is modern slavery?

The prevalence of modern slavery

Modern Slavery Act 2015

Statutory guidance

Independent Anti-Slavery Commissioner

National Referral Mechanism

First Responder Organisations

Decision-making authorities

Support for victims

Reviews of the Act

Home Affairs Committee ten year review (2025)

House of Lords post-legislative scrutiny review (2024)

Government response to the report

Independent review of the Modern Slavery Act (2019)

Modern Slavery Act 2015 review: one year on (2016)

Further reading

Library briefings

Committee material

Parliamentary material

Wider stakeholder comment

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