The chapter examines the origins and nature of the Special Jurisdiction for Peace (JEP), and the role that international cooperation has had in its consolidation. Specifically, the chapter looks at the Colombian model of transitional justice and the mode of investigation of system crimes by the JEP, throwing light on the technical aspects pertaining to its work. The chapter argues that although the country has seen different forms of international cooperation, that proceeding from the European Union in recent years has been central insofar as it helped consolidate the institutions of the JEP and shielded the Comprehensive System for Peace from political attacks from the government. Nonetheless, the chapter also presents a critical perspective on international cooperation in support of peacebuilding institutions, since the funds that sustain the functioning of the JEP do not proceed from the sovereign state implementing the peace accords.