The British Columbia judge overseeing a landmark reference case on Canada's polygamy law has given a green light to hearing evidence from Angela Campbell, a law professor at McGill University who has said that the criminal prohibition against polygamy is harmful.

Lawyers representing the attorneys-general of Canada and B.C., as well as counsel for the group Stop Polygamy in Canada, argued Tuesday in B.C. Supreme Court that Prof. Campbell was not qualified to be an expert witness in the case.

Prof. Campbell sat in the witness box as lawyers grilled her about her résumé and research experience and techniques.

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Reading from transcripts of interviews conducted by Prof. Campbell, Leah Greathead, a lawyer for the province, said the lengthy questions often only received a "yeah" in response.

"In our profession, that would be called leading," Ms. Greathead said.

Lawyers for the province said the attorneys-general would be willing to have Prof. Campbell's interviews with Bountiful residents admitted into the proceeding but objected to her affidavits being included.

Chief Justice Robert Bauman said both her affidavits and transcriptions of her interviews would be admitted.

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Introduced in court as a legal scholar and researcher who has studied the ban on polygamy and Bountiful in particular, Prof. Campbell visited the southeastern B.C. community in 2008 and 2009 to interview women as part of her research.

She has filed two affidavits with the court outlining her opinion that the prohibition against polygamy is harmful.

"The criminalization of polygamy has had adverse outcomes for Bountiful's residents," Prof. Campbell wrote in her affidavit. "That is, residents of Bountiful feel ashamed, stigmatized and highly anxious because their way of life is branded as criminal."

She said the women she spoke with told her that marriages involving adolescent girls are discouraged, and some women were allowed input into who they marry. She said if there are harms associated with polygamy, the law appears unable to prevent them and instead makes it more difficult for people living in polygamous communities to seek help.

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Brian Samuels, a lawyer for Stop Polygamy in Canada, noted Prof. Campbell was trained in law, and not in sociology, psychology or ethnography. He also questioned her expertise in the sort of qualitative, interview-based research she conducted in Bountiful, even though she currently teaches a research course at McGill.

Mr. Samuels asked Prof. Campbell whether she was aware that Bountiful has a reputation for secrecy and that people in such closed religious communities might be encouraged to be deceptive to outsiders. Prof. Campbell said that she was aware.

Mr. Samuels than asked how Prof. Campbell could trust what the women in Bountiful had told her.

"I think it's acceptable for the researcher to accept the veracity of the statements that were told to her … so long as there is critical reflection on the comments and the research methods," she said.

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Prof. Campbell acknowledged that she never asked the women she interviewed whether the community's religious leaders had asked them to speak or told them what to say. She was concerned asking such a question would be insulting.

George Macintosh, a court-appointed amicus, who will argue against the polygamy law, described Mr. Samuels's questioning as a "continuing attack."

The B.C. criminal justice branch charged the leaders of Bountiful, Winston Blackmore and James Oler, with practising polygamy but the charges were quashed in court because several legal opinions had recommended against such charges previously.

The province then asked the B.C. Supreme Court last year to examine whether the prohibition against polygamy violates the Charter of Rights and Freedoms, as Mr. Blackmore and Mr. Oler claim.

The provincial and federal governments maintain that polygamy inherently fosters sexual abuse and discrimination against women. Those arguing against the law say that criminalizing multiple marriages violates the guarantee of religious freedom and stigmatizes people living in polygamous communities.

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In addition to experts lining up in both camps, the court will hear testimony from people currently living in polygamous marriages, as well as women and children who have left polygamous communities.

Earlier in the day, Judge Bauman delayed his decision about whether video affidavits from 14 ex-wives and children from polygamous relationships can be broadcast publicly. Their content has already been reported, but the Crown does not want them broadcast on TV or the Internet unless witnesses specifically consent.

One of the witnesses, Ruth Lane, complained after an edited clip of her testimony appeared on a local newspaper website.

That matter was put off until Ms. Lane can address the court by telephone.

With a report from The Canadian Press