Few episodes in recent times have proved so rich in surprises as the Severe Acute Respiratory Syndrome (SARS) saga of spring 2003. Among a number of oddities, consider for the moment just one. Only weeks before the SARS crisis publicly erupted in March 2003, the United Nations was in acrimonious disarray. A divided Security Council had failed to agree on strategies to disarm Saddam Hussein and to impede a war against him. Yet just as pundits were announcing the death of the UN, SARS suddenly gave one branch of it—the World Health Organization (WHO)—renewed energy and respectability. It is the most basic axiom of international relations that states are jealous to preserve their prerogatives and “sovereignty,” of insisting that other countries and organizations do not meddle in their internal affairs. But the Global Alert and Respiratory Unit of the WHO managed not only to forge an unprecedented degree of cooperation among disease laboratories scattered across the planet, it was also able to elevate itself to the extraordinary position of global prosecutor, judge and jury. Governments—in mainland China, Hong Kong, Taiwan, Vietnam, Singapore, and Canada—quaked at its pronouncements, feared its travel advisories, and pleaded to be released from them. To use a ubiquitous metaphor of the time, the “war” against SARS was the epitome of the UN ideal: a worthy defense against a common, unequivocal foe, under the auspices of a truly pan-national organization.