Which of the following judges of the Supreme Court of India is famously known as the ‘Green Judge’?

The correct choice is: “Justice Kuldip Singh”

Justice Kuldip Singh (Supreme Court judge, 1988–1996) earned the title ‘Green Judge’ for a series of landmark environmental judgments, many in public interest litigation filed by M.C. Mehta. These include the Taj Trapezium case (ordering polluting industries near the Taj Mahal to relocate or switch to cleaner fuel), the Vellore Citizens Welfare Forum case (1996), which adopted the ‘precautionary principle’ and ‘polluter pays principle’ as part of Indian law, and orders on vehicular pollution and industrial effluents.

“Justice V.R. Krishna Iyer” and “Justice P.N. Bhagwati” are best known as pioneers of public interest litigation and prisoners' and workers' rights; “Justice B.N. Kirpal” was a Chief Justice of India who also heard forest cases (the Godavarman matter), but the ‘Green Judge’ label belongs to Kuldip Singh.