The judicial review refers to the power of judiciary to declare invalid any law of the legislature or the actions of the executive, whether at the Union level or at the state level, if they find such a law or action is against the Constitution. Judiciary can determine the constitutional validity of any legislation or action of the executive in the country, when it is challenged before them. The Supreme Court of India has also ruled that the core or basic principles of the Constitution cannot be changed by the Parliament. The Supreme Court and the High Courts have the power to interpret the Constitution of the country and have the power of judicial review.