This contribution reviews shortcomings of the grave breaches system as they have evolved in recent jurisprudence and state practice. It first considers textual problems identified by the International Criminal Tribunal for the former Yugoslavia in this respect and evaluates the solutions applied by the Tribunal. Second, the article will assess shortcomings of law and practice related to the application of universal jurisdiction addressing the question of whether failures are political or legal. In the light of such shortcomings, the article will discuss the issue of universal jurisdiction over war crimes as a permissive rule of customary law. Finally, some conclusions are drawn, with a view to outlining some of the remaining problems for the prosecution of serious violations of international humanitarian law, and developing effective solutions.