For the first time in U. S. history, in the decision of Marbury v. Madison, the Supreme Court determined that an act of Congress was unconstitutional. What is the significance of the Supreme Court's ability to determine the
constitutionality of an act of Congress of a law?

The significance of the Supreme Court's ability to determine the constitutionality of an act of Congress of a law is that, through Marbury v. Madison, the Supreme Court is the final interpreter of the United States Constitution, in such a way that it becomes the guarantor of its compliance through the judgment of the constitutionality of the laws passed by Congress.

In this way, the Supreme Court controls the legislative action through a check of the constitutionality of the norms, thus giving itself the power to define whether or not a norm will be operative.

the answer is false my dude