This chapter discusses Articles 37–42, considering legal implementation and international cooperation and assistance. Article 37 recognizes that treaties, agreements, and other constructive arrangements between States and indigenous populations reflect legally important entitlements that have to be honoured by applying the standards of modern treaty law, while taking into consideration the facts of cases at hand and later developments, and including the interests of other parties than the original ones. In addition, the United Nations Declaration on the Rights of Indigenous Peoples (UNDRIP) might be a declaration ‘only’, but it cannot be simply considered as ‘just another’ non-binding argument. Large parts of Articles 37–42 — particularly Article 37, relating to the right that treaties concluded with indigenous peoples are honoured and respected by States, and Article 40, proclaiming the right of indigenous communities to access to justice and to remedies — do have customary international law character, while other parts also reflect more than moral or political commitments ‘only’.