Judicial review is a process under which executive, legislative and administration action are subject to review by the judiciary. The best known power of supreme cout is judicial review and the ability of the court is to declare a Legislative or executive act in violation of the constitution . The court established this doctrine in case of Murbary vs Madison (1803)

Also we can said that Judicial Review is a power of court that to check the constutionality of any act of the parliament or any action of statutory body.

principle to be followed in Judicial Review :

1.presumption of constitutionality

2.Between two interpretation the one which declares constitutionality is to be preferred. 

3. The courts gives it opinion in concreate and does not answer any academic question.