In 1980, Tulsi started practicing criminal law. In 1987, he was appointed as a senior advocate. Three years later in 1990, he was designated Additional Solicitor General of India. Since 1994, he is the President of the Criminal Justice Society of India. Tulsi has fought many notable cases. He has represented the Indian government more than ten times in the Supreme Court. He represented Indian government in cases like the constitutional validity of the now extinct Terrorist and Disruptive Activities (Prevention) Act, and cases related to the assassination of Rajiv Gandhi former Prime Minister of India. He represented Tamil Nadu Government on Sankararaman Murder Case in which Seer of Kanchi Mutt Jeyendra Saraswathi Was involved, "for them a Brahmin is above the law!" was the famous quote was given during interview with Reddif.