John was a successful merchant in Nova Scotia, carrying on part of the family business started by his father and uncle.
His battle with the legislature was carried out to a great degree in the press making him a popular hero and a well known Nova Scotian.
A subsequent stand with the Tories during the "Brandy Dispute" of 1830 made him unpopular enough to make his future attempts at re-election unsuccessful.
John Alexander Barry was fascinated by aboriginal people in the area, with whom it is believed he traded early in his merchant career.
He became popular by his lectures, principally to Halifax audiences, on the customs, artifacts, and chiefs of the Miꞌkmaq and other North American Indians.