Ewing was educated at Illawarra College in Wollongong, then Oakwoods at Mittagong, and finally night school in Sydney.

[2] In 1895, he contested the New South Wales Legislative Assembly seat of Tweed as an Independent Protectionist, but was unsuccessful.

[2] In the federal election of 12 December 1906, he contested a Tasmanian seat in the Senate as an Anti-Socialist, but was defeated by a small margin.

[10] Ewing was made a King's Counsel in 1914, and in September the following year resigned his seat in parliament to accept an appointment as a Judge of the Supreme Court of Tasmania.

As Judge of the Supreme Court, he was involved in the 1915 Tasmanian Royal Commission into the public debt sinking fund; charges brought against Victor Ratten in 1918.

[11] He also conducted the 1920 Royal Commission in New South Wales into the imprisonment of twelve Industrial Workers of the World members.

[12] From November 1923 to June 1924, Ewing was appointed Administrator of Tasmania, while awaiting the arrival of the new governor Captain Sir James O'Grady.