The world's first permanent war crimes court starts work tomorrow but faces opposition from Russia, China and the United States, which wants immunity for its overseas peacekeeping troops and other US officials.
The Dutch-based International Criminal Court (ICC) will have authority over genocide, crimes against humanity and war crimes as of July 1, 2002.
Human rights groups have hailed the court's creation as the biggest milestone for international justice since top Nazis were tried by an international military tribunal in Nuremberg after World War Two.
But the United States wants to keep its peacekeepers out of reach of the ICC and has threatened to stop the UN mission in Bosnia if it did not get its way.
The 15-nation UN Security Council faces a midnight deadline to renew the Bosnia mission, set up in 1995 to train a multi-ethnic police force after Bosnia's three-year war that gave rise to the term "ethnic cleansing."
Washington has threatened to veto the resolution unless its peacekeepers and US officials are provided with immunity from the ICC.
Critics say Washington is trying to cripple the tribunal before it starts, saying its campaign is against the court itself, which has been ratified by 69 countries.
The United States says the court would infringe on national sovereignty and could lead to politically motivated prosecutions of its officials or soldiers working outside US borders.