Judicial review is the term used to reference a process by which courts in the USA can evaluate any act by the legislative or the executive branches. And if it is found that the act is in any way contrary to the principles of the Constitution the judiciary can declare the act as invalid.
The process of Judicial Review gave the judiciary powers to curtail the other two branches from doing anything that was not permitted by the Constitution. Though judicial review is associated with the Supreme Court, most state and federal courts have the authority to use it to uphold the Constitution.
With the process of Judicial Review, the US became the first nation to give the Judiciary supreme powers over the executive and the legislature to annul any act that went against the Constitution.