Two years ago, in May 2007, UNAIDS and WHO issued new guidelines on HIV testing. Prepared to meet the demands of the AIDS pandemic and the prospects of extending the benefits of antiretroviral therapy to regions where such treatment had been all but out of reach, the new guidance was the product of an extended period of sometimes acrimonious controversy both within the two UN agencies and globally. Those pressing for change had argued that a paradigm of testing that had emerged at a time when little could be done for those infected with HIV was inappropriate to the current moment. Those who viewed with skepticism, if not hostility, the claims that current practice and stringent ethical standards had become an impediment to effectively confronting the challenge of AIDS saw in the proposed changes a threat to the bedrock ethical principles of informed consent. In the end, of course, decisions about HIV testing will be taken by nation - states, with the recommendations of international organizations constituting but one element, however important, that will shape policy. Nevertheless, an examination of the history and the dynamics of the recent controversy and its outcome will provide a unique resource to those faced with policy choices; it will also provide a unique opportunity to lay bare the complex and politically charged relationships evolving between public health and human rights.