Amicus curiae — literally "friend of the court" — is an advocate or expert appointed by a court to assist with a matter, typically where the adversarial parties are unable to present a complete picture (e.g. where one party is unrepresented, where a matter involves complex public interest, or where the court needs independent technical input).
In Indian practice, the Supreme Court and High Courts appoint amici curiae in a range of situations: death-row confirmations where the condemned is unrepresented; public interest litigations where expert input is valuable; reference matters where the court seeks independent legal opinion on complex constitutional questions. Being appointed amicus is an honour; the role carries prestige and the expectation of pro bono or nominal-fee service.
The amicus is not aligned with any party. Their role is to present the full legal picture — including arguments that may disadvantage one side — so the court can decide on complete material. This distinguishes amicus from counsel representing a specific party's interest.
Amicus briefs and arguments are often cited in landmark judgments. In Indian constitutional cases — particularly before the Supreme Court — an amicus's contribution can shape the outcome significantly. The practice of amicus appointment is a safety valve: ensures that even in adversarial systems, the court has access to complete argumentation on matters of significant public importance.