Deborah Margaret Ryland Coyne (born February 24, 1955) is a Canadian constitutional lawyer, professor, and author.

She was an employee in the Prime Minister's Office of John Turner, before spending two years teaching constitutional law at the University of Toronto Law School; she has also worked for the Business Council on National Issues, the Ontario Health Service Appeal and Review Board, and the Immigration and Refugee Board of Canada.

[2] Their child, Sarah Elisabeth Coyne, is Trudeau's only daughter, and attended the Wharton School of the University of Pennsylvania.

Coyne was nominated in March 2007[7] as the Liberal Party of Canada candidate in Toronto Danforth but withdrew later in the year.

[8] In 2008, she sought the federal Liberal nomination in the riding of Don Valley West but withdrew in favour of Rob Oliphant.

"[14] Coyne was the Green Party of Canada candidate in the Ottawa riding of Carleton for the 2015 federal election, where she finished fourth with just over 3% of the vote.