James Hannen, Baron Hannen PC FRS, (19 March 1821 – 29 March 1894), English judge, son of a London merchant, was born at Peckham.
He was educated at St Paul's School and at Heidelberg University, which was famous as a school of law. Called to the bar at the Middle Temple in 1848, he joined the home circuit. At this time he also wrote for the press, and supplied special reports for the Morning Chronicle. Though not eloquent in speech, he was clear, accurate and painstaking, and soon advanced in his profession, passing many more brilliant competitors. He appeared for the claimant in the Shrewsbury peerage case in 1858, when the 3rd Earl Talbot was declared to be entitled to the earldom of Shrewsbury as the descendant of the 2nd earl; was principal agent for Great Britain on the mixed British and American commission for the settlement of outstanding claims, 1853–1855; and assisted in the prosecution of the Fenian prisoners at Manchester.
In 1868, Hannen was appointed a judge of the Court of Queen's Bench. In many cases he took a strong position of his own, notably in that of Farrar v. Close (1869), which materially affected the legal status of trade unions and was regarded by unionists as a severe blow to their interests. Hannen became judge of the Court of Probate and Court for Divorce and Matrimonial Causes in 1872. By virtue of being the Probate Judge, he became President of the Probate, Divorce and Admiralty Division by operation of the Judicature Acts when three courts became part of the new High Court of Justice. Here he showed himself a worthy successor to Cresswell and Penzance.