A study of the separation of powers (legislative, executive, and judicial) in Australia at the Commonwealth and the State level including three Australian States, Queensland, Victoria and New South Wales. The separation of powers (SOP) theory from Locke and Blackstone is used for the SOP theory in Australia. In practice, the English rather than the American system of government and SOP is the model used for the Australian Commonwealth Government and SOP. The Commonwealth SOP is used as a guide for the States SOP. Queensland, Victoria and New South Wales are case studies used to compare and contrast with the Commonwealth. The concept of the SOP in Australia is articulated by the High Court and is derived from the Blackstonian SOP theory rather than the Federalist SOP theory. The implementation of the SOP theory into practice is problematic. The SOP theory is used as a conceptual framework to understand current events. The advantages and disadvantages or problems of the Commonwealth model are presented as a guide for the States. The same structure is used for the study of the three States in the form of the advantages and disadvantages or problems of the SOP at the State level. The entrenchment of the SOP at the State level will help to partly overcome the problems highlighted in the case study chapters. The federal SOP situation is better than at the State level but the entrenchment of Bills of Rights at the Commonwealth and State levels would help to counter the trend in reduction of civil rights. The SOP is important in protecting citizens from the abuse of government power. The lack of separation of powers, especially separation of judicial power at State level, has meant the increasing abuse of powers by the executive and the executive dominating the other two branches of government.