Law was commissioned into the 71st Foot in 1809. He was promoted lieutenant in 1811 and captain in 1821. In 1822 he transferred to the 1st West India Regiment. He later transferred to the 83rd Foot and in 1824 to the Ceylon Regiment. In 1834 he was promoted major and transferred to the Royal Newfoundland Veteran Companies, also being appointed commander of the garrison in Newfoundland. His responsibilities also required him to play a political role between the departure of Governor John Harvey and the arrival of Sir John Gaspar Le Marchant where he assumed the role as colonial administrator. Law dispensed relief to the victims of the 1846 fire at St. John's.
