This paper examines the conceptual development of the philosophical justifications for tyrannicide. It posits that the political philosophy of tyrannicide can be categorised into three distinct periods or models, the classical, medieval, and liberal, respectively. It argues that each model contained unique themes and principles that justified tyrannicide in that period; the classical, through the importance attached to public life and the functional role of leadership; the medieval, through natural law doctrine; and the liberal, through the postulates of social contract (...) theory. Subsequent analysis of these different models however, reveals that these historical models are unable to provide a sufficient philosophical basis for a contemporary justification of tyrannicide. In Part II, it will be contended that a reinvigorated conception of self-defence, a theme common to all three models, when coupled with the modern notion of universal human rights, may provide the foundation for a contemporary theory of tyrannicide. (shrink)