Judicial review refers to a political process wherein the judicial branch of government is given enough powers to check the authority of other branches like the executive and legislative branches for example.  Through the judicial review process, some kind of check and balance is implemented in terms of the activities of the other branches.  In the case of democratic countries for example, the powers and authorities of each branch of government is based on a written law or constitution.  It is through the constitution that the judicial branch can review specific concerns regarding each branch of government.  With judicial review, a certain law or bill that is passed by the legislative government may be deemed invalid or unconstitutional.  In the same, executive powers are also checked and/or limited by judicial review if these powers are not within the stipulated limits of a higher authority like a written constitution.

The concept or process of judicial review is attributed to the principle of power separation between the different branches of government.  Each branch of government has basically its own powers and limitations and in order that every aspect is considered in a particular concern, many governments rely on their judicial branches to make a review on policies and laws to determine if the concern of another branch is valid and legal or otherwise.  Different governments and countries may have their own interpretations and specifications regarding judicial review, but the core concept remains in the fact that the judicial branch is given authority to check on other branches whether they are exercising their powers based on the written constitution.  For other countries, the common rule of law may be based on religious concepts and beliefs.  The basis for judicial review will then be attributed to these concepts.  In the same way, the other branches of government are also considered to be equal with each other along with the judicial branch in terms of authority and power.  In this way, a valid check and balance system is in place to prevent abuse or misuse of power and authority.