Trade ministries from the World Trade Organization's (WTO's) 144 member states are presently deciding which public services to open to foreign competition under the complex liberalisation rules of the general agreement on trade in services (GATS). A frequent criticism of the WTO system is that it reduces national autonomy over public policy. However, respect for national sovereignty is asserted in the GATS treaty. Here, we examine claims made by the WTO and others that GATS exempts public services and does not require their privatisation. We discuss trade treaty processes that can subject public services to commercial rules, the treaty's flexibility with respect to national autonomy, and the effect of GATS in situations in which national autonomy is not protected. We conclude that national autonomy over health policy is not preserved under GATS, and that accordingly, there is a role for international standards that protect public services from the adverse effect of trade and market forces.