Section 377: Unnatural offences—
Whoever voluntarily has carnal intercourse against the order of nature with any man, woman or animal, shall be punished with transportation for life, or with imprisonment of either description for a term which may extend to ten years, and shall also be liable to fine.
Explanation—Penetration is sufficient to constitute the carnal intercourse necessary to the offence described in this section.
IMPORTANT CASE LAW
Navtej Singh Johar v. Union of India, (2018) 10 SCC 1: “Section 377 IPC, so far as it penalizes any consensual sexual relationship between two adults, be it homosexuals (man and a man), heterosexuals (man and a woman) or lesbians (woman and a woman), cannot be regarded as constitutional. However, if anyone, by which we mean both a man and a woman, engages in any kind of sexual activity with an animal, the said aspect of Section 377 is constitutional and it shall remain a penal offence under Section 377 IPC. Any act of the description covered under Section 377 IPC done between two individuals without the consent of any one of them would invite penal liability under Section 377 IPC.”