This is the fourth volume in our series on ‘Internal Displacement in a Changing World Order’. It examines how state policies addressing internal displacement have evolved since the Cold War, analysing 588 policies across 86 countries adopted between 1989 and 2022. The authors find that policy adoption surged during the peak of the liberal international order, particularly in the 2000s and 2010s, driven by major displacement crises, international advocacy, and normative frameworks like the 1998 UN Guiding Principles on Internal Displacement, the 2006 Kampala Convention, and the IASC Durable Solutions Framework. While most countries address displacement through broader vulnerable population frameworks, the content of IDP-specific policies has shifted over time. Provisions establishing camps and granting formal IDP status have declined since 2018, whereas service provision guarantees expanded dramatically between 2003 and 2018, likely reflecting state-building efforts in conflict-affected nations. As the liberal international order weakens, the authors question whether policy adoption will slow without international pressure and normative consensus, while suggesting that existing policies may serve as valuable tools for domestic advocates to hold governments accountable.