- Indira Gandhi v. Raj Narain: Tested the 39th Amendment, related to election disputes and judicial review. - Minerva Mills v. Union of India: Tested the 42nd Amendment, particularly regarding the Parliament's power to amend the Constitution and led to the reinforcement of the Basic Structure doctrine. - Kihoto Hollohan v. Zachillu: Tested the 52nd Amendment (Anti-defection law). - P. Sambamurthy v. State of A.P.: Tested the 32nd Amendment (special provisions for Andhra Pradesh).