The power of judicial review allows the Supreme Court to rule whether or not laws made by the legislative or executive branch are constitutional or unconstitutional.
The power of judicial review was established in the Supreme Court case Marbury vs. Madison. Judicial review gives the Supreme Court the power to strike down laws that are contrary to the US Constitution. This power ensures that the rights of citizens are protected, as they cannot be convicted under a law that is considered unconstitutional. This is still the most important function of the Supreme Court today.