Legal systems such as those in the United States and Canada, which include fundamental rights of political morality in their constitutions, present an interesting and difficult problem for legal positivists. Are such moral standards to count among the existence or validity conditions of laws, or are they better understood as fundamental objectives or justification conditions which laws may or may not achieve or respect in practice? The first option, known as inclusive legal positivism, expands the traditional positivist separation thesis to mean that although there is no necessary connection between law and morality in general, it is possible that in some systems it is a necessary truth that laws reproduce or satisfy certain demands of morality. The second option, known as exclusive legal positivism, denies this possibility, and maintains instead that it is never a necessary condition that laws reproduce or satisfy certain demands of morality, even if such demands are constitutionally recognized. On the exclusive account, in the context of constitutional states such as the U.S. and Canada, the separation thesis is expanded to mean that there is no necessary connection between the existence and content of laws and the demands of political morality typically included in constitutions. In this thesis I defend exclusive positivism and argue that it best follows from the traditional positivist commitment to separate existence conditions oflaw from justification conditions of law, and further, avoids what I take to be decisive problems with inclusive positivism. Specifically, I argue that Joseph Raz's notion of a directed power, and not reliance on an inclusive rule of recognition, best explains the duty of judicial review in Charter cases. The fundamental rights of political morality recognized in the Charter are best understood as constitutional objectives which all subordinate laws in Canada ought to respect, yet may fail to do so in practice. Finally, I argue that the concepts, distinctions, and arguments deployed in the internal positivist debate are also of value in the wider and ongoing debate between H.L.A. Hart and Ronald Dworkin over the nature of law. / Thesis / Master of Arts (MA)