The thesis is concerned with understanding the influence of constitutional philosophy on contemporary political practice. The thesis questions whether the Australian polity has an established account of what constitutes the underpinning philosophy of the Constitution and, more importantly, if this philosophical inheritance has any enduring impacts. The thesis refutes claims that Australian constitutionalism is devoid of political philosophy or underpinned by an innate utilitarianism, arguing that the Constitution has a rich and diverse philosophical heritage. More specifically, the thesis contends that Australian constitutionalism is predominantly shaped by two philosophical traditions that can be traced to the founders’ decision to combine elements of English and US constitutional thought. The first three chapters of the thesis discuss how these two traditions shaped the development of the Constitution, contributing to Australian understandings of critical constitutional concepts such as the separation of powers, the foundations of national sovereignty and the best mechanism to secure individual rights. Furthermore, by tracing the philosophical origins of the Constitution, the thesis shows that the two predominant influences on the development of Australian government are often at theoretical tension. Having established the Constitution’s rich and diverse philosophical heritage, the thesis then attempts to understand if the theoretical tensions in Australian constitutionalism manifest in contemporary political practice.