The law-making power is traditionally assigned to the Legislature. However, the increasing involvement of Presidents in law-making has generated much interest and controversies among scholars, in recent times. This paper examines the extent of the President’s law-making power both in Nigeria and the United States of America. It is argued that the increasing exercise of legislative power by Presidents, arising from delegation of such power by the Legislature, legislative abdication of power or executive usurpation of power, has virtually turned Presidents into supermen, exercising all powers of government. The paper, however concludes that if presidential legislative power is properly utilized and controlled, it could become a useful instrument for the attainment of sustainable constitutional democracy.