Why is judicial review an important aspect of the us government?

Judicial review is an integral part of our constitution. It is so important because any executive or legislative action which goes against the spirit of the constitution will become null and void.

The principle of judicial review is comprised within the system of Checks and Balances that oversees that the principle of the division of powers is maintained in the US and that none of the three branches of power: legislative (Congress), executive (Goverment) or judiciary (Court system) gathers excessive power so that can overrule the other two.

The principle of judicial review places the executive and legislative power under the surveillance of the judiciary. A court with authority to exercise this principle can abolish laws and goverment decision, if it considers that such actions are violating the Constitution.