The Uniform Income Tax cases are landmarks in Australian political and constitutional history. The four interrelated Acts, which prompted the litigation by which the Commonwealth sought to secure sole authority for the imposition and collection of income tax, were described by critics as ‘revolutionary’ when first introduced into the Parliament. In response, the Government claimed that the measures were necessary to meet the ‘serious crisis’ presented by the current phase of World War II. On the existence of the crisis at least, there was no disagreement; the Bills received assent on the day after the battle of Midway Island. The rejection of the challenge in the first case and the limited success of the plaintiffs in the second affected the course of Australian federalism and engaged the High Court in some constitutional questions of the greatest difficulty, with implications well beyond the financial provisions of the Constitution.

With hindsight, the cases symbolise a turning point in Australian constitutionalism. In the first case, the national emergency, the perception of federalism as an interim form of government to which a unitary system was to be preferred and a literal approach to the judicial interpretation of the Constitution combined to produce an outcome that had scant regard to the federal nature of the Constitution. By 1957 the national emergency was over and much else had changed besides. Australia was on the way to political acceptance of federalism, however grudging.