The present research work is focused on the legal analysis of the relevant articles of the International Criminal Court's Statute regarding the obligation of cooperation between States for the punishment of serious crimes against humanity and war. Judicial development, starting with ad hoc Tribunals and arriving at causes at various stages of proceedings still ongoing at the International Criminal Court, opens the doctrinal and comparative national debates, seeking to elaborate on specific topics such as requests for assistance during preliminary investigations, assistance during inquiries, consultations, confidential information, Court assistance to States parties participating in the statute, competing requests, suspending the execution of a request, the role of the Prosecutor and the non-assistance of some States that for political and not only reasons impede the development and operation of international criminal justice.