They deal with the treatment of the sick & injured, prisoners of war and the protection of civilians under occupation
What the US/UK etc have done is violate the UN charter which prohibits aggressive acts when not justified. From a more knowledgable person than myself:
'The jus ad bellum is founded primarily on Article 2 and Chapter VII (articles 39-51) of the United Nations charter. This insists that "All Members shall settle their international disputes by peaceful means" (Article 2(3)) and that "All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any State" (Article 2(4)). It allows for "the inherent right of individual or collective self-defense" (Article 51).
Many states claim that humanitarian intervention constitutes an exception to the prohibition on the use of force. However a 1973 study on humanitarian interventions found "that most have occurred in situations where the humanitarian motive is at best balanced, if not outweighed, by a desire to <...> reinforce socio-political and economic instruments of the status quo". Thus 'humanitarian intervention' is often used as cover for a breach of Article 2(4).'
http://www.darkcoding.net/strategy/law.phpHowever:
The United States takes a different view concerning the relationship between international and domestic law than many other nations, particularly in Europe. Unlike nations which view international agreements as always superseding national law, the American view is that international agreements become part of the body of U.S. federal law. As a result, Congress can modify or repeal treaties by subsequent legislative action, even if this amounts to a violation of the treaty under international law. The most recent changes will be enforced by U.S. courts entirely independently of whether the international community still considers the old treaty obligations binding upon the U.S. Additionally, an international agreement that is inconsistent with the U.S. Constitution is void under domestic U.S. law, the same as any other federal law in conflict with the Constitution, and the Supreme Court could rule a treaty provision to be unconstitutional and void under domestic law, although it has never done so. The constitutional constraints are stronger in the case of CEA and executive agreements, which cannot override the laws of state governments.
http://en.wikipedia.org/wiki/Treaty