Answer:
Review and possibly invalidate laws and acts.
Step-by-step explanation:
Judicial Review is a power that is not explicitly written in the US Constitution. It was created in the case Marbury v. Madison in which the US Supreme Court, as the Court that protects the US Constitution, decided that the Court is the responsible for reviewing laws or acts of the executive and legislative branches to see if they are compatible with the Constitution. If a law or executive decision is incompatible with the Constitution, it will be considered unlawful or invalidated by the Court.
The Judicial Review is a part of the checks and balances system that comes with the separation of powers and three branches system.