Wikipedia has lots of information about him. He was Hong Kong's Attorney-General from 1865 to 1873:
In 1862, facing crippling financial losses, Pauncefote decided to go and practise as a barrister in Hong Kong. In 1865, he was appointed acting Attorney General and in 1866 became the Attorney General of Hong Kong. As attorney general, he served as acting Chief Justice and acting Puisne Judge on a number of occasions.
In Hong Kong Pauncefote was involved in a major case involving the rights of enslaved coolies to free themselves. He ended up being sued for false imprisonment in the Supreme Court of Hong Kong. In 1871, Kwok A Sing, a coolie on board a French ship the Nouvelle Penelope which had sailed from Macau killed the master and took over the ship. Kwok was arrested in Hong Kong to be extradited to China. Kwok made a habeas corpus application seeking his release. Chief Justice John Jackson Smale ordered his release on the basis that Kwok was entitled to take any necessary steps to secure his freedom. Pauncefote, as Attorney General of Hong Kong, then had Kwok re-arrested to be tried for piracy. Smale again ordered Kwok's release on the basis the second arrest breached the first habeas corpus order. Kwok then sued Pauncefote for damages for false imprisonment under the Habeas Corpus Act. Kwok almost won with the British jury finding 4-3 in Kwok’s favour. Because a majority of five was needed to find in Kwok’s favour the verdict was treated as a verdict for Pauncefote.
In 1874, Pauncefote was appointed Chief Justice of the Leeward Islands and knighted.
From: http://en.wikipedia.org/wiki/Julian_Pauncefote,_1st_Baron_Pauncefote