The use of force across state borders to protect human rights is one of the greatest contemporary dilemmas, not only in international law, but also in ethics, international relations and politics. This issue has become more acute since decolonisation and the end of the Cold War, which led to the creation of new states comprised with mixed ethnic communities or facing a different political reality. Some of these ''new'' states cannot control their territory or face the rise of insurgency, ethnic separatism, massacre and ethnic cleansing. Other states do function adequately, but in some cases, certain ethnic, religious or linguistic communities are suppressed, with their most basic human rights, including right to life, being violated by the state itself or other factions within the state, whose behaviour the state acquiesces or cannot control.

Against this background, the issue of whether contemporary international law permits states to use force against other states for the purpose of protecting human rights, sometimes without prior Security Council authorisation, becomes extremely important. This study, by examining the relevant international law principles and rules, and the practice of the Security Council and of states, attempts to provide an answer as to where modern international law stands regarding the legality of the use of force to protect human rights, and whether there are any conditions regulating its legitimate use.