The public health consequences of the conflict in Iraq will likely continue after the violence has subsided. Reestablishing public health security will require large investments in infrastructure and the creation of effective systems of governance. On the question of governance, the allocation of powers in the new constitution of Iraq is critical. Given the ease with which public health threats cross borders, the constitution needs to grant to the federal government the legal authority to manage such threats and simultaneously meet international requirements. Unfortunately, the draft constitution does not accomplish this objective. If politically possible, the constitution should be amended to provide the federal government with this authority. If not possible, the Iraqi federal government would have two options. It could attempt to use alternative constitutional powers, such as national security powers. This option would be contentious and the results uncertain. Alternatively, the federal government could attempt to establish collaborative relationships with regional governments. Residual sectarian tensions create potential problems for this option, however. Reflecting on the Iraqi situation, we conclude that other federalizing countries emerging from conflict should ensure that their constitutions provide the federal government with the necessary authority to manage threats to public health security effectively.