Why the Supreme Court of India cannot on its own criminalize marital rape

Even though I support the legislative criminalization of marital rape in India, I think it is possible to persuasively argue in favor of the legal principle that while the Judiciary under the Indian Constitution can strike down a law that creates a criminal offence on the ground of arbitrariness, it cannot add language to a statute that would result in creating an offence or in criminalizing acts or acts by an exempted (by the legislature) category of persons and that the latter does not fall within the powers and jurisdiction of the Supreme Court.

Criminalizing conduct is a legislative function and a Court cannot usurp this function.

In case a criminal law offends Article 14 by arbitrarily exempting a category of persons, then the Court can strike down the entire law compelling the legislature to re-enact the law. This would of course require a well-functioning legislature, which India lacks.

See 
“As stated above, the Supreme Court held as far back as 1812 in United States v. Hudson and Goodwin, and several times since then, that there are no federal common law offenses and that before someone can be punished as a criminal, his conduct must “plainly and unmistakably” run afoul of a federal criminal statute.

As the court has also stated, “because of the seriousness of criminal penalties, and because criminal punishment usually represents the moral condemnation of the community, legislatures, and not courts, should define criminal activity.”

The court deviated from this sound reasoning in Dirks, a move that has seemingly been tolerated by Congress. The court should not compound its error by going one step further, even if it seems like a small step. If Congress wishes to criminalize insider trading or expand the scope of current criminal liability, it can and should do so.”

From http://dailysignal.com/2016/09/30/supreme-court-should-make-decision-that-upholds-that-congress-not-agencies-should-make-criminal-law/

And see this interesting discussion on the judicial criminalization of marital rape in Nepal at http://www.nepalkanoon.net/2013/08/08/concept-of-criminalization-penalization-and-principle-of-legality-in-our-judicial-discourse-2/