He did his masters in Law from Cambridge University and was called to the bar from middle Temple in london.
Born in Tezpur, Assam, his father, Nirmal Chandra Chatterjee, was a prominent lawyer, intellectual, and Hindu revivalist and nationalist around the time of India’s independence, and his mother, Binapani Debi ran the home. Nirmal Chandra Chatterjee was one of the founders and one-time president of the Akhil Bharatiya Hindu Mahasabha. In 1948, when the Communist Party of India was banned by the Jawaharlal Nehru led Indian National Congress government in India, and its party leaders arrested, Nirmal Chandra Chatterjee formed the All India Civil Liberties Union, and agitated for their release. In the process, he came close to Jyoti Basu, in spite of continuing ideological political differences between the two.
Somnath was educated at Mitra Institution School, Presidency College and then the University of Calcutta in Calcutta. He also attended Jesus College, Cambridge and graduating with a B.A. in 1952 and a M.A. in 1957, both in law, has been awarded an honorary fellowship by the college in 2007. He was called to the bar from the Middle Temple in London and took up legal practice as an advocate at the Calcutta High Court before joining active politics.
As he was know for his independent ides and fearless approach to politics,he defied party dictate in parliament and didn’t resigned from the post of Lok Sabha Speaker in 2008.after withdrawing support to Congress led UPA government his party CPM asked him to resign from the post of Lok Sabha Speaker so that he can vote against the UPA government during test of strength in Lok Sabha,in 2008.
He was married to Renu Chatterjee, on 7 February 1950. The couple have one son,and two daughters.
His financial integrity was admirable.As speaker of lok Sabha when he shifted to the official residence at 20 Akbar Road, he stopped the practice of paying for toiletries and tea from the national exchequer.He bore all expenses on these items from his pocket.During foreign tour, he bore the expenses of any accompanying family members.