Territorial self-governance remains a persistent feature of contemporary conflict resolution. Existing research has identified a number of exogenous factors that impact the sustainability of such
arrangements, including previous levels of violence, the level of economic development in a given territory, or the strategic importance thereof. We argue that a hitherto neglected variable
in the legal form of the autonomy agreement – that is, the degree to which it has been ‘legalized’
by the language and processes prescribed in the agreement. Based on an in-depth qualitative
evaluation, we assess the degree of legalization of 228 post-conflict autonomy agreements signed between 1945 and 2019. Quantitative survival analyses and Cox regression models show that a higher degree of legalization has a positive and significant effect on peace durability.