This contribution analyzes the rights to justice, truth and reparation in the Inter-American Human Rights System. It argues that in transitional justice contexts, these rights not only entail the obligation to investigate, prosecute and punish human rights violations, but also to exercise due diligence in preventing those violations; guaranteeing non-repetition; clarifying the truth; and providing security. These obligations are intermingled, and their inter-dependence reinforced in a transitional context. It also suggests a balance between the conventionality control and the national margin of appreciation in contexts of transition from armed conflict towards a negotiated peace. In particular, the paper advances that these contexts require the latter doctrine be re-assessed: states are better placed to design and implement the necessary mechanisms and platforms to move to a lasting peace; leaving the parameters of the conventionality control to a minimum core of prohibitions.