A new guide has been launched to help companies uphold workers' rights to freely join or form trade unions in complex international supply chains.

The guide from the Ethical Trading Initiative (ETI) has been produced in response to what it says is the current lack of clear, practical guidance on this issue - and draws on ETI's experience of supporting its members with freedom of association and collective bargaining.

Freedom of association is the right for workers and employers to establish and join trade unions of their own choosing, without prior authorisation and interference from government or from one another.

This right is enshrined in both the Universal Declaration of Human Rights and the International Labour Organization (ILO) conventions, and is a central clause in ETI's internationally recognised Base Code of labour practice.

"We recognise that companies often grapple with the practicalities of freedom of association in complex international supply chains," explains Debbie Coulter, ETI head of programmes.

"This guide provides concrete steps to help them uphold workers' right to freely join or form trade unions, including establishing a policy, understanding local labour laws and setting up monitoring systems."

Included in 'Freedom of association in company supply chains: a practical guide' are tools that companies can use as part of the auditing process. This might include making sure that auditing teams include someone with experience of labour and trade union affairs, and that they hold face-to-face interviews with workers.

But it also shows why companies need to go beyond a compliance approach, highlighting the importance of strong, ongoing relationships with suppliers, trade unions and NGOs.

It also includes case studies on setting up worker hotlines in China, dealing with institutional corruption in Mexico, and the challenges of state-controlled unions in China and Vietnam. It is free to download from the resources section of ETI's website.