A polygamy charge against the leader of Bountiful, a fundamentalist breakaway commune in southeastern British Columbia is unfair and should be thrown out because he wasn't given "fair notice," a court has heard.

Winston Blackmore's lawyer Joe Arvay argued in B.C. Supreme Court on Monday that the provincial government doesn't have the right to criminally charge his client — or any resident of the commune — for historical acts of polygamy.

The cutoff point, said Arvay, should be a 2011 reference question that concluded polygamy laws did not violate the Charter of Rights and Freedoms. That decision provided constitutional clarity to Canadians involved in the controversial practice.

"The whole point of having a reference (case) was to give those people fair notice that their conduct was lawful or unlawful," Arvay said.

"It would be unfair to the people of Bountiful to prosecute them for conduct that they were led to believe by many people in authority was lawful."

Blackmore is one of the heads of Bountiful, B.C. — a remote fundamentalist community whose name has become synonymous in Canada with the practice of polygamy.

Winston Blackmore appeared outside the courthouse in Creston, B.C., on Oct. 9, 2014 along with a number of his daughters, who came to support him. (CBC)

Arvay told the court that Blackmore's 25 alleged marriages took place between 1975 and 2001, predating the reference question by a decade.

Blackmore sat quietly in court Monday watching the proceedings. His shock of white hair, neatly combed back, contrasted his sharp black suit. He held a ball cap in his lap emblazoned with the name of his family business: J. R. Blackmore & Sons Ltd.

'Shopping' for a prosecutor

Arvay also argued that Blackmore's polygamy charge should be quashed because the government acted improperly by appointing successive prosecutors until it got the recommendation it wanted.

"This is yet another case of, to use the vernacular, 'shopping' for a prosecutor to do something the first prosecutor wouldn't do," said Arvay.

In 2007, special prosecutor Richard Peck concluded that polygamy was the root cause of Bountiful's alleged issues. But rather than recommend charges he suggested a constitutional question be referred to the courts to provide more legal clarity.

Instead, the province opted to appoint a succession of other prosecutors until one eventually recommended taking legal action in 2009.

Those charges were thrown out later that year, after Arvay successfully argued the province had acted improperly. The province answered by posing a reference question to the B.C. Supreme Court on the constitutionality of polygamy.

The Crown was expected to present its case later Monday, arguing that circumstances have changed since Peck's recommendations and in the lead up to the appointment of special prosecutor Peter Wilson in 2012.

New evidence has come to light following a police raid on a Texas fundamentalist ranch in 2008, and the legal grey area surrounding polygamy has been resolved in the interim with the 2011 reference question, the Crown is expected to say.

None of the allegations has been proven in court.