In 1993, Mr. Gopal Subramanium was designated a Senior Advocate (the equivalent of a Queen's Counsel in the UK) suo motu by the Supreme Court, one of the youngest to be so designated in the Supreme Court's history. His varied work-experience includes:
- Acting as counsel (in 1991 - 1992) to a judicial commission headed by Justice J. S. Verma (then a judge of the Supreme Court) to inquire into security lapses leading to the assassination of Mr. Rajiv Gandhi, the former Prime Minister of India.
- Acting (in 1993) as "prosecuting counsel for the Central Bureau of Investigation (CBI)" in the trial of persons accused of setting of a series of bomb blasts in Bombay. He acted as CBI's counsel in this matter till 2012 when appeals in this trial were heard by the Supreme Court.
- Acting as a special commissioner appointed by the Supreme Court in 1994-1995 to investigate into allegations on wrongful detention of persons in mental hospitals in the State of Assam.
- In 2001, he was appointed as counsel to a judicial commission headed by Justice K. Venkataswamy (a former Supreme Court judge), to inquire into sting operations carried out by a news publication to expose corruption in defence procurement transactions.
- Shortly thereafter, he acted as the Special Public Prosecutor in the prosecution of accused of the terrorist attack on the Indian Parliament in 2001.
Between 2005 and 2009 he held the office of Additional a Solicitor General of India, and subsequently served as the Solicitor General of India from 2009-2011. During his tenure as Solicitor General, he also served as the Chairman of the Bar Council of India.
During his tenure as a law officer, Subramanium was honoured with the National Law Day Award for Outstanding Jurist, presented to him in 2009 by the President of India, for his consistent professional excellence and adherence to the highest traditions of the Bar. Subramanium is a visiting professor at the University of Delhi, and was awarded an honorary Doctorate in Law (in 2013) by the Central University of Orissa, Koraput for his contributions to the development of law in India. He is also an associate member of the prestigious, 3 Verulam Buildings barristers'chamber of London Senior counsel.