In finally taking the vexed issue of war with Iraq to the United Nations, U.S. President George W. Bush has presented the organization with a double-edged test of credibility. Will it lift its performance and remain relevant to U.S. foreign policy on Washington's terms, or in doing so will it be seen as bending to U.S. will without demanding American compliance with global norms from arms control to environmental regimes and international criminal justice?

The U.N. as the moral legitimacy and political credibility to mediate, moderate and reconcile the competing pulls and tensions that still plague international relations. But it lacks the military muscle to enforce its edicts.

The United States, which is both today's supreme power and the historic nation of laws, is the world's de facto sheriff, enforcing international norms and law, often with the aid of deputy sheriffs, in various parts of the world. U.S. rejections of specific global regimes undermine respect for a world order based on collective norms and international law: Even the sheriff must respect law and be seen to be impartial in dispensing frontier justice.