He served as attorney general and chief justice of a number of British colonies in the late 19th and early 20th centuries.

His last position before retirement was as chief justice of the British Supreme consular court in the Ottoman Empire.

[5] The other son, Charles Loughlin Meyler Brent O'Malley, was a lieutenant colonel in the Royal Artillery.

As Attorney General, O'Malley was allowed to accept private cases which did not conflict with his official position.

In 1881, he, together with Thomas Hayllar, QC, were engaged by the Imperial Maritime Customs to defend, in the British Supreme Court for China and Japan sitting at Canton, a British employee of the customs service, Edward Page, who was accused of murder for killing a Chinese smuggler.

[12] In 1900 he was advanced to be Chief Judge of the Supreme Consular Court for the Dominions of the Sublime Ottoman Porte.