Forced labour fundamentals · Guide

The ILO's 11 indicators of forced labour, explained for supply-chain teams

The International Labour Organization's eleven indicators are the most widely used vocabulary for recognising forced labour. This guide explains each one in supply-chain terms: what it can look like at a supplier site, where evidence tends to sit, and why indicators are prompts for investigation rather than conclusions.

Published by Libera Europe · Last reviewed 5 October 2026

The definition the indicators serve

The ILO Forced Labour Convention, 1930 (No. 29) defines forced labour as all work or service which is exacted from any person under the threat of any penalty and for which the said person has not offered himself voluntarily. Two elements matter: involuntariness (the worker did not freely agree, or cannot freely leave) and menace of penalty (something is held over them).

The eleven indicators, published by the ILO in 2012, are observable signs that one or both elements may be present. They are written for labour inspectors, NGOs and companies — people who need to recognise a situation before anyone has established what it legally is.

The eleven indicators at a glance

ILO indicators of forced labour with supply-chain examples. Descriptions are Libera's plain-language summaries of the ILO publication.
Indicator	What it means	Where supply-chain teams can look
1. Abuse of vulnerability	Workers who lack language skills, legal status, local knowledge or alternative livelihoods are exploited because they have few options.	Migrant and seasonal workforces; workers whose visa is tied to one employer.
2. Deception	Promises about pay, job type, hours, location or conditions that are not kept once the worker arrives.	Recruitment contracts versus contracts signed on arrival; recruitment advertising.
3. Restriction of movement	Workers are locked in, confined to the site or dormitory, or can only leave under escort.	Dormitory rules, gate logs, curfews, guarded exits.
4. Isolation	Workers are cut off from the outside world: remote sites, confiscated phones, no contact with family or community.	Remote agricultural, fishing, mining or construction sites.
5. Physical and sexual violence	Violence or the threat of it used to control workers or compel work.	Grievance records, worker interviews conducted safely off-site.
6. Intimidation and threats	Threats of dismissal, denunciation to immigration authorities, harm to family or loss of wages.	Disciplinary practice, supervisor conduct, worker testimony.
7. Retention of identity documents	Employers or agents hold passports, ID cards or work permits so workers cannot leave freely.	Document-holding policies, safe lockers with worker-held keys.
8. Withholding of wages	Wages are delayed, withheld or paid into accounts workers do not control, to keep them working.	Payroll records against bank records; end-of-contract payment practices.
9. Debt bondage	A debt — often from recruitment fees, advances or housing charges — that the worker cannot realistically repay ties them to the job.	Fee receipts, payroll deductions, loan arrangements with agents.
10. Abusive working and living conditions	Degrading, hazardous or unsanitary conditions that workers would not freely accept.	Dormitory inspections, health and safety records.
11. Excessive overtime	Hours beyond legal limits imposed under threat of penalty, including to meet production quotas.	Time records versus production targets; unpaid or unrecorded hours.

Why one indicator is not a finding

The ILO is explicit that the presence of a single indicator may in some cases imply forced labour, but in other cases several indicators taken together point to it. Excessive overtime alone can be a labour-rights violation without being forced labour; combined with retained passports and recruitment debt, it describes a worker who cannot refuse.

Indicators that travel together

Some combinations recur often enough that reviewers should look for the second indicator when they find the first:

Recruitment fees → debt bondage → withholding of wages (repayment through deductions). See recruitment fees and debt bondage.
Migrant workforce → retention of identity documents → restriction of movement. See identity-document retention.
Remote site → isolation → abusive living conditions.
Production pressure → excessive overtime → intimidation and threats about refusing it.

Where the evidence actually sits

Most indicators are invisible in supplier questionnaires: a supplier holding passports rarely says so. Evidence tends to sit in three places — documents (payroll, contracts, fee receipts), physical conditions (dormitories, gates, lockers) and the workers themselves. The last is the most direct and the hardest to reach safely, which is why confidential worker voice matters. See worker voice in due diligence.

Using the indicators in a risk assessment

Use structural factors (country, sector, recruitment model) to decide where to look first.
Use the indicators to decide what to look for once you are there.
Record which indicators were checked, how, and what was found — including 'not checked'.
Treat an indicator cluster as a reason to investigate, not a verdict.

The full method is in the forced labour risk assessment guide.

Sources and method

Written by Libera Europe from the primary sources below. Where a fact could not be confirmed in a primary source it was left out. This is general information, not legal advice; laws and guidance change, so check the current official text.

Libera produces risk indicators as prompts for human review, not findings. It does not determine that forced labour occurred, does not guarantee compliance with any law and is not legal advice.