He represented the Antigonish riding of Nova Scotia, from 1867 to 1869, along with William Hallett Ray, as an Anti-Confederate and, from 1869 to 1873, as a Liberal-Conservative.

The son of Allan MacDonald and Christina Cameron, he was educated at Saint Francis Xavier University and called to the Nova Scotia bar in 1855.

[1] MacDonald served as President of the Queen's Privy Council for Canada and Minister of Militia and Defense in 1873.

Later that year, he resigned his seat in parliament to accept an appointment to the Nova Scotia Supreme Court.

McDonald served as puisne judge in the Supreme Court from November 1873 until he retired from the bench in 1893.