In the context of Federalism in India, which one of the following Supreme Court judgments explicitly reaffirmed the principle that the federal structure of the Indian Constitution cannot be altered by a unilateral amendment by the Union, thus protecting the principle of federalism as a part of the Basic Structure Doctrine?
1
Golaknath v. State of Punjab (1967)
2
S. R. Bommai v. Union of India (1994)
3
Indira Nehru Gandhi v. Raj Narain (1975)
4
Minerva Mills v. Union of India (1980)