Justice, in its broadest sense, is the foundation on which efforts to tackle modern slavery internationally, nationally and locally rest. For Target 8.7 of the United Nations Sustainable Development Goals (SDGs) to be fully realized, it is clear that effective measures in the context of justice require serious consideration of how interventions are delivered, and not only what measures are adopted. As such, States may seek guidance on effective implementation of justice policies to support the achievement of the commitments to which they have agreed. The role of Delta 8.7’s Justice Policy Guide is to assist policymakers in assessing “what works” to end modern slavery in the context of justice.