It is not the whole Act which would be held invalid for being inconsistent with Part III of the Constitution but only such provision of it, which violates the Fundamental Rights, provided that the part which violates the fundamental rights is separable from that which does not violate them.

But if the valid portion is so closely mixed up with the invalid portion that it cannot be separated, the Court will declare the entire Act void. This process is known as Doctrine of Severability or Separability.

• A.K. Gopalan vs State of Madras - The Supreme Court held that the preventive detention minus section 14 of the Preventive Detention Act, 1950 was valid as the omission of section 14 from the act would not change the nature and object of the act, therefore the rest of the act would remain valid and effective.
   
• State of Bombay vs F.N. Balsara - It was held that the provisions of the Bombay Prohibition Act, 1949 which were declared as void did not affect the validity of the entire act.
   
• R.M.D.C. vs Union of India - The Court held that section 2(d) of the Prize Competition Act was broad enough to include competitions of gambling nature as well as competitions involving skill, and also held that provisions of the act were severable and it struck down only those provisions which related to competitions of gambling nature.

Also Read:

• Doctrine Of Severability: A Scalpel Rather Than A Bulldozer
• Doctrine Of Severability: Door To Judicial Review
• Overview of Doctrine of Severability