Khanna is also the nephew of a former judge of the Supreme Court of India, Justice Hans Raj Khanna, who propounded the basic structure doctrine in 1973 and famously delivered the lone dissenting judgement in the ADM Jabalpur v. Shiv Kant Shukla case, popularly known as the Habeas Corpus case, in 1976 and was superseded to the office of the Chief Justice of India by M. H. Beg at the behest of the then Prime Minister Indira Gandhi, protesting which he resigned from the court in early 1977.