Answer:
Judicial review is the power of courts to decide the validity of acts of the legislative and executive branches of government. If the courts decide that a legislative act is unconstitutional, it is nullified. ... The power was first asserted by Chief Justice John Marshall in 1803, in the case of Marbury v. Madison.
Second, due to its power of judicial review, it plays an essential role in ensuring that each branch of government recognizes the limits of its own power. Third, it protects civil rights and liberties by striking down laws that violate the Constitution.