Hannen held the following appointments in China and Japan: • Acting Assistant Judge of the
British Supreme Court for China and Japan based in
Yokohama (1871 to 1874) •
Crown Advocate, Shanghai (1878 to 1881) • Judge of the
British Court for Japan (1881 to 1891) • Acting
Chief Justice of the British Supreme Court for China and Japan (1881 to 1883) •
Chief Justice of the British Supreme Court for China and Japan (1891 to 1900) • British
Consul-General, Shanghai (1891 to 1897) From 1871 to 1874 he was appointed Acting Assistant Judge of the
British Supreme Court for China and Japan and was based in
Yokohama, period during which he assisted
Oe Taku during the
Maria Luz incident. Following this, he returned to
Shanghai to private practice. In 1878 he was appointed
Crown Advocate of the Supreme Court, a position akin to that of a colonial
attorney general. The Crown Advocate was allowed to accept cases from private clients that did not affect their duties as Crown Advocate. In 1881, he was appointed as Judge for the
British Court for Japan in
Yokohama. Before taking up the appointment, he acted as
Chief Justice of the British Supreme Court for China and Japan for more than one year until the new Chief Justice, Sir
Richard Rennie, returned from long leave to take up the post. In 1891, on Rennie's retirement, he was appointed as Chief Justice of the British Supreme Court for China and Japan and
Consul-General in
Shanghai. This appointment was the first and only time the Chief Justice also served as
Consul-General. There was much opposition from foreign residents in China to the amalgamation of the positions. The opposition was not based on Hannen's ability but rather that it was inappropriate for one man to hold a judicial and executive position at the same time. The position of Chief Justice and Consul General were separated in 1897 and Hannen continued as Chief Justice.
George Jamieson who had been Assistant Judge and Consul was appointed Consul-General.
Frederick Bourne took over the position of Assistant Judge. Hannen was knighted on 18 July 1895 at
Windsor Castle and received the
Jubilee Medal in 1897. ==Death==