Human trafficking legislation and policy have increasingly been developed in jurisdictions across the world since being defined in the United Nations Convention Against Transnational Organized Crime in 2000. In this context, the UK Modern Slavery Act 2015 sought to distinguish the actions of the UK with the then Prime Minister, Theresa May claiming that the legislation would ‘lead the way in defeating modern slavery and preserving the freedoms and values that have defined our country for generations’ (May, in Defeating modern slavery, 2016). International coordination and engagement are an important component of the UK Modern Slavery Strategy, to support other countries in the development of their national legislation. Taken together these mechanisms contribute to a mode of global policymaking through transnational policy communities. Drawing on primary research with people involved in policy development from ten Commonwealth countries, this article identifies the opportunities and limitations of policy making within this space. The domination of the global north in human trafficking policy casts a particular view of the problem of human trafficking that creates barriers to recognising or acknowledging traditions or customs which can embed exploitation and fails to understand the impact of anti-slavery policy narratives that are interpreted through colonial legacies. In this context, although global governance cooperation between countries around modern slavery can be significant, it faces many challenges, not least the practicalities and the aptness of the UK’s leading role in international anti-trafficking and anti-slavery policymaking, which this paper questions.