The election of the World Health Organization (WHO) Director-General is governed by its Constitution in Article 31. Candidates must be appointed by the Health Assembly on the nomination of the Executive Board. Unlike other international organizations in which the decision-making process is largely informal—such as the IAEA and WTO—the WHO procedures were formalized in the 1990s to include: clear deadlines; an initial screening of all candidates; short-listing by secret ballot in case of more than five candidates; compulsory secret ballot voting both in the Board and the Assembly; and a limit of two terms of office of five years each. However, beginning in 2006, some regional groups strongly demanded the introduction of a compulsory rotation of the post of Director-General among the WHO’s regions. The equally strong rejection of that request by other regional groups led to an increasingly polarized debate in the governing bodies of the WHO.