This paper examines the ‘joint decision trap’ in the Australian federation. Fritz W. Sharpf (1988) first identified the trap through an examination of German federalism and later policy-making in the European Union. Scharpf’s thesis has been widely applied including test cases in Canada and unitary states, but the Australian case remains woefully understudied. This paper tests the joint decision trap framework against intergovernmental relations in Australia, focusing on the Council of Australian Governments (COAG) Reform Council. It specifically tests the cases of: capital cities, healthcare, and water management reform in an effort to explicate lessons for the future.