In 1903, Sinha became Standing Counsel to the Government of India overriding the claims of an English Barrister.

His legal practice in 1908 was so lucrative that accepting government's invitation meant a cut in his annual income of £10,000.

Sinha's first inclination was to turn down the viceroy's invitation, but Jinnah and Gokhale convinced him to accept the job.

The first World War slowed promulgation of the amended code as drafted by the committee; it was ultimately enacted in 1921.

In 1917, Sinha returned to England to work as an Assistant for Secretary of State, Edwin Samuel Montagu.

In the same year, he was made Parliamentary Under-Secretary of State for India and also raised to the peerage as Baron Sinha of Raipur in the Presidency of Bengal.

In 1926, Sinha went back to England and joined the Judicial Committee of the Privy Council in London but bad health forced him to return to India.

At the Calcutta session of the Congress in 1896 - he brought a proposal that no ruler of any Indian State should be deposed without an open judicial trial.