He was the most prominent of the five advocates who appeared on behalf of James Somersett in the case which determined, in 1772, the legal status of slaves in England.

[1] He came to prominence because of his performance in 1772, in Somersett's case, and shortly afterwards was made King's Counsel.

In 1797 he was made Recorder of Liverpool, and for many years was treasurer of Lincoln's Inn and a leading parliamentary lawyer.

He fell ill, in 1813, and his legal collection was purchased by the government for £8,000 and deposited in the British Museum.

His works were: A catalogue of his manuscripts was compiled by Sir Henry Ellis, and published in 1818.