<P> At several other points in the debates at the Constitutional Convention, delegates made comments indicating their belief that under the Constitution, federal judges would have the power of judicial review . For example, James Madison said: "A law violating a constitution established by the people themselves, would be considered by the Judges as null & void ." George Mason said that federal judges "could declare an unconstitutional law void ." However, Mason added that the power of judicial review is not a general power to strike down all laws, but only ones that are unconstitutional: </P> <P> But with regard to every law however unjust, oppressive or pernicious, which did not come plainly under this description, they would be under the necessity as Judges to give it a free course . </P> <P> In all, fifteen delegates from nine states made comments regarding the power of the federal courts to review the constitutionality of laws . All but two of them supported the idea that the federal courts would have the power of judicial review . Some delegates to the Constitutional Convention did not speak about judicial review during the Convention, but did speak about it before or after the Convention . Including these additional comments by Convention delegates, scholars have found that twenty - five or twenty - six of the Convention delegates made comments indicating support for judicial review, while three to six delegates opposed judicial review . One review of the debates and voting records of the convention counted as many as forty delegates who supported judicial review, with four or five opposed . </P> <P> In their comments relating to judicial review, the framers indicated that the power of judges to declare laws unconstitutional was part of the system of separation of powers . The framers stated that the courts' power to declare laws unconstitutional would provide a check on the legislature, protecting against excessive exercise of legislative power . </P>

Where did the concept of judicial review come from