Which principle is central to the Inter-American "due diligence" doctrine?

The principle central to the Inter-American "due diligence" doctrine is the requirement for accessible domestic remedies. This doctrine obligates states to take necessary and effective measures to prevent, investigate, prosecute, and sanction human rights violations. It emphasizes that states must ensure that individuals have the means to seek justice and redress for violations of their rights through accessible domestic legal mechanisms.

In the context of international human rights, due diligence requires that states not only refrain from violating rights themselves but actively create an environment where individuals can pursue legal actions to remedy violations. This includes having systems in place that are not only available but also effective and efficient in addressing claims of human rights abuses. Accessibility often encompasses practical aspects such as affordability, simplification of procedures, and knowledge of legal rights.

The other principles mentioned, while important in their own right, do not capture the essence of due diligence in the same way. Mandatory state intervention is more about proactive measures that a state must take, protection of cultural heritage pertains to preserving assets of cultural significance, and encouragement of political participation relates to fostering democratic engagement rather than addressing individual rights violations through legal avenues. Therefore, the choice regarding accessible domestic remedies aligns most closely with the core idea of the due diligence doctrine in the Inter-American system.