Amicus Curiae is a Legal phrase derived from Latin which means “friend of the court”. It refers to someone, not a party to a case, who volunteers to offer information on a point of law of some other aspect of the case to assist the court in deciding the judgment.
The figure of Amicus Curiae originated from Roman law. Then it was incorporated into English law and it was later extended to common law systems including India.
In any criminal matters if the accused is unrepresented, then an advocate is appointed by the court to defend the accused and argue in favor of him. Amicus Curiae can be appointed by the court in civil matters too; court appoints amicus curiae in public matters also. Majority of the Amicus Curiae who are appointed by the Indian courts are senior advocates, who have much experience in civil/criminal matters. Law academicians can also be appointed as Amicus Curiae. Courts relay on statements of experts to understand the cases effectively. The role of an amicus curiae as stated by Lord Salmon is as follows:
“I had always understood that the role of an amicus curiae was to help the court by expounding the law impartially, or if one of the parties were unrepresented, by advancing the legal argument on his behalf.”
Section 45 in the Indian Evidence Act, 1872, talks about the opinions of experts. Amicus don’t have to necessarily be in the legal field. In Siddhapal Kamala Yadav v State of Maharashtra the opinion of the doctors against the accused that Yadav was normal and was not in an unsound mind when he was committing murder was taken by the court as vital evidence and the appeal given by him was thereby dismissed. Some of the most famous Amicus Curiae in recent times are Shyam Divan in the Odisha chit fund case, Gopal Subramaniam in the Sree Padmanabhaswamy Temple case, Raju Ramachandran in the Kasab case. Delhi High Court suspended both the defence and the prosecution lawyers for driving the witnesses to turn hostile in Court On Its Motion v State on 7 August, 2007. In the said case, Advocate Arvind Nigam was appointed as amicus curiae by the Delhi High Court for securing justice. In State (Delhi Administration) v Pali Ram Delhi High Court appointed a handwriting expert to render justice.
In Novartis v. Union of India & Ors Shamnad Basheer, a professor of Intellectual Property Rights filed an intervention application before the Supreme Court and provided academic assistance to the Court. In 2012, Delhi High Court’s decision on Section 377 was appealed to Supreme Court, 16 teachers from various universities in India filed an intervention to the Supreme Court.
The above instances lead to the fact that the interventions of amicus curiae in many cases have helped the judges to fully & clearly understand the facts of the case and provide the right judgment.
 Allen V. Sir Alfred Mc. Alpine & Sons Ltd
 http://startup.nujs.edu/blog/indian-professors-as-amicus-curiae-industry-academia-divide-and-the-birth-of-the-practitioner-academic/ 9th paragraph.
1979 AIR 14, 1979 SCR (1) 931
 CIVIL APPEAL Nos. 2706-2716 OF 2013