The phrase 'Public Interest Litigation' (PIL) signifies legal action taken to defend the interests of the public or a segment thereof.
Key Finding: The term 'Public Interest Litigation' was notably popularized and first used in its modern context by Prof. Abram Chayes, a prominent legal scholar. While the concept evolved significantly, particularly in India with contributions from figures like Justice P.N. Bhagwati, the specific terminology's origin is attributed to Chayes.
Therefore, the term "Public Interest Litigation (PIL)" was first used by Prof. Abram Chayes.