CALGARY -- Journalistic ethics are to be discussed today at the defamation trial involving a former television journalist, a columnist and one of Canada's largest media companies.

Arthur Kent alleges Postmedia, the National Post and columnist Don Martin defamed him when he was campaigning to win a Calgary legislature seat for the Progressive Conservatives in the 2008 provincial election.

The column written by Martin ran under the headline "Alberta's 'Scud Stud' a 'Dud' on Campaign Trail.

It portrayed him as a loose cannon who was difficult to deal with and said a number of key campaign members were threatening to quit.

Jeffrey Dvorkin was accepted as an expert on journalistic ethics during morning testimony.

Dvorkin, a lecturer and director of the University of Toronto's journalism program, is a former managing editor and chief journalist at CBC radio and was the first news ombudsman for National Public Radio in the U.S.