Where would the power of judicial review be found if it's not in the Constitution?

The concept of judicial review is not specifically stated in the Constitution. Therefore, we can’t find specific wording about it in that document. The concept of judicial review developed from the Marbury v Madison case in 1803. In this case, the Supreme Court ruled it had the right to determine whether or not laws were unconstitutional.

Some of the basis for this concept comes from a law passed by Congress. The Judiciary Act of 1789 created our court system. In the Judiciary Act of 1789, the Supreme Court would have the power to review certain decisions made by other courts. This, to some degree, opened the door to the idea that courts could have the power of judicial review.

John Marshall also was a Federalist. He very likely interpreted the Constitution in a loose manner. This allowed him to support the concept of judicial review. Federalists tended to view the Constitution in a loose manner, giving them the power to interpret the meaning of the Constitution.