What is modern slavery? Definitions, forms and scale

Modern slavery is one of the most serious human rights issues in global supply chains – and one of the least well understood.

The term is widely used in legislation, investor questionnaires, and corporate reporting obligations, but what it actually means in a business context, and how it differs from related terms like forced labour and human trafficking, is often unclear.

This page explains the key definitions, the different forms modern slavery takes, its scale globally, and – critically – what these concepts mean in practice for businesses operating or sourcing internationally.

For a full guide to what your business is expected to do about it, see: Forced labour & modern slavery: a complete guide for business.

Modern slavery: the definition

Modern slavery does not have a single agreed legal definition. It is an umbrella term – used most prominently in UK and Australian legislation – that brings together a set of related but distinct legal concepts: forced labour, human trafficking, debt bondage, servitude, and in some frameworks, forced marriage.

What these concepts share is a common core: a person’s freedom has been removed. They are in a situation they cannot refuse or leave because of threats, violence, coercion, deception, or abuse of power. The exploitation may be for labour, for commercial sexual purposes, or for other forms of gain – but the defining feature is the removal of voluntary choice.

The ILO, Walk Free and the International Organization for Migration (IOM) – who together produce the most widely cited global estimates – define modern slavery for measurement purposes as encompassing forced labour and forced marriage. In a commercial supply chain context, modern slavery is primarily encountered in the form of forced labour, which is why the two terms are often used interchangeably in business and legislative settings, even though they are technically distinct.

Forced labour: the specific definition that matters most for business

The most operationally important definition for businesses is that of forced labour, established by the International Labour Organization in Convention No. 29 (1930) and reaffirmed in the 2014 Protocol:

“All work or service which is exacted from any person under the menace of any penalty and for which the said person has not offered himself voluntarily.”

This definition has three elements, all of which must be present:

Work or service – this covers any type of work, in any sector, formal or informal, legal or illegal. It includes domestic work, agricultural labour, factory work, construction, fishing, and service industries.

Menace of penalty – the penalty does not have to be physical violence. It includes threats of violence or denunciation to authorities, withholding of wages or documents, loss of housing, psychological coercion, and debt bondage. Any form of coercion that makes a person feel they cannot leave qualifies.

Involuntariness – the worker did not freely consent to the work, or having consented initially, is no longer free to leave. Consent given under deception – for example, where a worker was promised one type of work or pay level and experienced something different – does not count as voluntary.

This ILO definition is the foundation of international law on forced labour and underlies the business and human rights standards that companies are increasingly expected to apply, including the UN Guiding Principles on Business and Human Rights (UNGPs) and the OECD Guidelines for Multinational Enterprises.

The forms modern slavery takes in supply chains

Modern slavery is not a single phenomenon. In a supply chain context, it manifests in several distinct but often overlapping forms:

Forced labour

The broadest and most common category in commercial supply chains. Workers are compelled to work through coercion, threats, or the removal of freedom. It occurs across agriculture, manufacturing, construction, domestic work, fishing, and the services sector. It can be state–imposed (for example, government–mandated labour in certain countries’ cotton sectors) or privately imposed by employers, recruiters, or labour brokers.

Debt bondage

Often described as the world’s most widespread form of modern slavery. Workers borrow money – frequently to pay recruitment fees to obtain employment – and then find that the debt grows faster than it can be repaid, or that the terms of repayment were never clearly established. In this situation, the debt itself becomes the mechanism of control: workers feel unable to leave until the debt is cleared, even when working conditions are exploitative. Debt bondage is particularly prevalent among migrant workers who have paid fees to recruitment agencies in order to work abroad.

Human trafficking for labour exploitation

The ILO and UN define human trafficking as the recruitment, transportation, transfer, harbouring, or receipt of people through threat, force, fraud, deception, or abuse of power, for the purpose of exploitation. In a supply chain context, this most commonly involves workers being deceived about the nature, location, or conditions of work they are recruited for, and then finding themselves unable to leave. The movement of workers across borders – or even within a country – can constitute trafficking where deception or coercion is involved.

Importantly: a worker does not have to have been physically moved or have crossed a border for labour trafficking to have occurred. Deceptive recruitment and coercive control at the worksite can constitute trafficking even when the worker has not travelled far.

Servitude and domestic servitude

Servitude refers to an obligation to work that is imposed through coercion and from which the person cannot free themselves. Domestic servitude – where workers, often women and migrant workers, are employed in private homes and subject to control, confinement, and exploitation – is a significant risk in global supply chains, particularly in household and personal services.

Child labour in its worst forms

Not all child labour constitutes modern slavery – international standards permit certain forms of light work for older children. However, the worst forms of child labour, as defined by ILO Convention No. 182, do fall within the modern slavery umbrella. These include work performed under conditions equivalent to slavery or forced labour, hazardous work, and the use of children in trafficking.

How these forms connect: the continuum of exploitation

In practice, the forms described above rarely appear in isolation. A worker who is trafficked across a border typically ends up in a situation of forced labour. A worker in debt bondage may have originally been recruited through deceptive means that constitute trafficking. A child working in dangerous conditions may be doing so because their family is in a situation of debt bondage.

For businesses, this means that identifying modern slavery in supply chains requires looking at the full picture of how workers were recruited, how they are managed, what control mechanisms are in place, and what the actual conditions of work are – not simply checking whether any single indicator is present.

The ILO has identified eleven indicators of forced labour which, taken together or in sufficient number, provide strong grounds for concluding that forced labour is present. These are:

1. Abuse of vulnerability
2. Deception
3. Restriction of movement
4. Isolation
5. Physical and sexual violence
6. Intimidation and threats
7. Retention of identity documents
8. Withholding of wages
9. Debt bondage
10. Abusive working and living conditions
11. Excessive overtime

No single indicator is necessarily conclusive on its own – context matters. But the presence of several indicators together, or of any indicator in a severe form, warrants serious investigation.

For practical guidance on applying these indicators in supply chain risk assessment, see: How to identify forced labour in your supply chain.

The scale: how prevalent is modern slavery?

The most authoritative global estimates come from the ILO, Walk Free, and the IOM, whose joint 2022 Global Estimates of Modern Slavery found:

49.6 million people were living in modern slavery on any given day in 2021
27.6 million were in situations of forced labour
17.3 million of those in forced labour were being exploited in the private economy – the sector most directly connected to commercial supply chains
3.3 million of all forced labour victims were children
Migrant workers are disproportionately affected, accounting for a share of forced labour victims far exceeding their proportion of the global workforce

These figures represent a significant increase from previous estimates. The ILO notes that the figures almost certainly undercount the true extent of the problem, given the hidden nature of forced labour and the methodological challenges involved in measuring it.

Where in the world

Modern slavery is present in every region of the world, including in high–income countries. The Asia–Pacific region accounts for the largest absolute numbers, reflecting population size and the concentration of global manufacturing supply chains. But as a proportion of population, prevalence is highest in parts of Africa, the Arab States, and Europe and Central Asia.

Critically for businesses: modern slavery is not only a problem in developing countries or distant supply chain tiers. Domestic servitude, forced labour in agriculture, and exploitation through labour recruitment agencies occur in the UK, across Europe, and in the US. Companies that focus their scrutiny only on overseas suppliers risk missing exploitation closer to home.

Which sectors carry the highest risk

Forced labour in the private economy is concentrated in specific sectors:

Agriculture and fishing – including fresh produce, seafood, cotton, cocoa, and tobacco supply chains
Manufacturing – particularly garments, electronics, and construction materials
Construction
Domestic work
Services – including hospitality, cleaning, and logistics

What modern slavery is not: common misconceptions

“Modern slavery only happens at the extremes”

The most severe forms of modern slavery – people kept in locked compounds, unable to communicate with the outside world – do exist, but they represent a fraction of the overall picture. The vast majority of forced labour involves more subtle forms of coercion: debt that cannot be repaid, documents that have been taken, wages that are withheld, threats that are implied rather than explicit. Workers in these situations may not identify themselves as victims of modern slavery and may continue to show up for work.

“We would know if it was happening in our supply chain”

Standard social audits are not designed to detect forced labour effectively. Workers in coercive situations are unlikely to disclose their circumstances to an auditor operating with the employer’s knowledge and cooperation. Identifying forced labour requires different approaches: confidential worker interviews conducted through trusted intermediaries, analysis of recruitment practices and wage payment systems, and engagement with civil society organisations that have established relationships in sourcing communities.

“It’s a problem for sectors we don’t source from”

Forced labour has been documented in virtually every sector connected to global supply chains, including sectors often assumed to be lower risk. The risk is shaped by labour practices, sourcing geography, and commercial relationships – not product category alone.

“Forced labour and child labour are the same thing”

They are related but distinct. Child labour refers to work that deprives children of their childhood, potential, and dignity, and is harmful to their development. The worst forms of child labour – including forced recruitment and hazardous work – overlap with modern slavery. But child labour that does not reach this threshold is a separate issue, addressed by a different body of international standards (ILO Conventions 138 and 182).

Modern slavery in law: the key frameworks

The legal treatment of modern slavery varies significantly by jurisdiction, which creates complexity for internationally operating businesses. The key frameworks are:

ILO Forced Labour Convention, 1930 (No. 29) and its 2014 Protocol – the foundational international standard, defining forced labour and establishing state obligations to eliminate it.

ILO Convention No. 182 on the Worst Forms of Child Labour (1999) – requires immediate action to eliminate the worst forms of child labour, including those that constitute forced labour.

UN Protocol to Prevent, Suppress and Punish Trafficking in Persons (the Palermo Protocol, 2000) – provides the internationally agreed definition of human trafficking and establishes obligations on states to criminalise it and protect victims.

UK Modern Slavery Act 2015 – the primary legislative framework in the UK, covering trafficking, slavery, servitude, and forced or compulsory labour. Section 54 introduces the supply chain transparency obligation requiring large businesses to publish annual modern slavery statements.

Australian Modern Slavery Act 2018 and Canadian Fighting Against Forced Labour and Child Labour in Supply Chains Act 2023 – follow the UK model of mandatory corporate reporting, with some differences in scope and required content.

EU Forced Labour Regulation and Corporate Sustainability Due Diligence Directive (CSDDD) – represent a shift from disclosure toward mandatory due diligence and market access restrictions, with broader scope and stronger enforcement mechanisms than existing UK and Commonwealth legislation.

For a full breakdown of what each piece of legislation requires in practice, see: Modern slavery legislation: what businesses need to know.

Why the terminology matters for your business

The terminology used in legislation, investor questionnaires, and reporting frameworks is not always consistent. The UK Modern Slavery Act uses “modern slavery” as a statutory term. EU legislation tends to use “forced labour.” US trade law refers to “forced labor” (American spelling) or “convict labor.” Some reporting standards use all three interchangeably.

For practical purposes:

When reporting under the UK Modern Slavery Act, you are reporting on the full modern slavery umbrella – forced labour, trafficking, servitude, debt bondage
When assessing supply chain risk under HRDD frameworks, forced labour (as defined by the ILO) is the primary operational focus
When responding to US trade compliance requirements (UFLPA), the relevant standard is “forced labor” as defined under US law, which is substantially equivalent to the ILO definition but with specific procedural implications for importers
When engaging with investors or ESG frameworks, both “modern slavery” and “forced labour” are typically used, and the underlying expectations generally align with ILO standards

If in doubt, the ILO Forced Labour Convention definition is the most widely recognised baseline and the one most closely aligned with international business and human rights standards.

Frequently asked questions

Is modern slavery the same as forced labour? Not exactly. Forced labour is one form of modern slavery. Modern slavery is a broader umbrella term that also encompasses human trafficking, servitude, debt bondage, and in some frameworks, forced marriage. In commercial supply chain contexts, the two terms are often used interchangeably because forced labour is by far the most prevalent form encountered – but they are technically distinct, and legislation in different jurisdictions uses the terms differently.

Is modern slavery the same as human trafficking? No, though they overlap. Human trafficking specifically involves the recruitment or movement of people through coercion or deception for the purpose of exploitation. Not all forced labour involves movement. A worker coerced into staying in a job they cannot leave – without having been recruited or moved deceptively – may be a victim of forced labour but not technically of trafficking. In practice, many victims of modern slavery in supply chains have experienced both.

Does modern slavery only happen overseas? No. Forced labour, domestic servitude, and labour trafficking occur in the UK, the US, across Europe, and in all high–income countries. In the UK, exploitation through gangmasters, labour agencies, and in agriculture and domestic work has been well documented. Any business sourcing domestically, or using domestic service providers, carries some level of risk.

What is the difference between modern slavery and poor working conditions? Poor working conditions – low wages, excessive hours, unsafe environments – are serious labour rights violations but do not in themselves constitute modern slavery unless the element of coercion or involuntariness is present. The key question is whether workers are free to leave. If they cannot leave because of debt, threats, document retention, or other forms of control, the situation moves from poor working conditions into the territory of forced labour or modern slavery.

What is debt bondage? Debt bondage occurs when a person’s labour is pledged as repayment of a debt, and the terms of that arrangement mean the debt cannot realistically be cleared. It is the world’s most widespread form of modern slavery, and in supply chain contexts is most commonly associated with workers who have paid recruitment fees to obtain employment. The ILO’s Fair Recruitment principles establish that workers should never pay fees to access employment – this cost should fall on the employer.

Further reading in this cluster

Forced labour & modern slavery: a complete guide for business
How to identify forced labour in your supply chain
Modern slavery legislation: what businesses need to know
How to write a modern slavery statement