B.C. Supreme Court has upheld Canada's polygamy laws, but says minors who end up in polygamous marriages should be exempt from prosecution.

In a 335-page decision released on Wednesday, Chief Justice Robert Bauman ruled in favour of the section of the Criminal Code outlawing polygamous unions.

In his ruling, Bauman said while the law does infringe on religious freedom, it is justified given the harm polygamy causes to children, women and society.

"I have concluded that this case is essentially about harm," Bauman wrote in the decision that was handed down Wednesday morning in Vancouver.

"More specifically, Parliament’s reasoned apprehension of harm arising out of the practice of polygamy. This includes harm to women, to children, to society and to the institution of monogamous marriage."

But he suggested the law shouldn’t be used to criminalize minors who find themselves married into polygamous unions.

The decision follows 42 days of legal arguments from a wide variety of groups interested in the constitutionality of Section 293 of the Criminal Code.

B.C. welcomes decision

The ruling was welcomed by B.C. Attorney General Shirley Bond in Victoria, who called the decision a "landmark" ruling that sends a clear message upholding the laws.

Winston Blackmore, a religious leader in the polygamous community of Bountiful near Creston, B.C., laughs with six of his daughters and some of his grandchildren in 2008. On Wednesday the B.C. Supreme Court upheld Canada's laws that make his polygamous relationships illegal. (Jonathan Hayward/CP)

"As Chief Justice Robert Bauman recognized, this case is about two competing visions — one of personal harm versus state intrusion. As he clearly found, there is profound harm associated with polygamy, particularly for women and children," said Bond.

Bond said she was pleased with the result, but would not say if B.C. intends to launch a third attempt to prosecute polygamists in the religious community of Bountiful.

The ruling was also welcomed by Brian Samuels, the lawyer for the group Stop Polygamy in Canada.

"I think it's a well reasoned and comprehensive decision," said Samuels.

Likewise, Canada's polyamorists — people with multiple partners outside a religious context — said they were relieved because Bauman said the law shouldn't apply to them unless they decide to formalize their unions.

"The formality of marriage is really not a big issue in the polyamorous community," said John Ince, the spokesman for the Canadian Polyamoury Advocacy Association.

But George MacIntosh, the lawyer appointed by the court to argue against the law, said the decision unfairly criminalizes the actions of consenting adults and he may appeal the decision.

"Three consenting adults who are causing no harm ought not to be committing a crime. The judge found that people in that circumstance are committing a crime if there was some celebration of the marriage, and we don't think that the section says that," said MacIntosh.

Failed prosecution led to test case

B.C.'s former attorney general Wally Oppal originally asked the court to answer two questions about Canada's polygamy laws: whether the law is consistent with the Canadian Charter of Rights and Freedoms; and what the necessary elements of the offence are.

Opponents of the legislation argued that the law is an affront to the most basic rights guaranteed under the charter – freedom of religion and the freedom of association.

But Bauman concluded "women in polygamous relationships are at an elevated risk of physical and psychological harm. They face higher rates of domestic violence and abuse, including sexual abuse."

Point of view: Do you agree with the polygamy ruling?

He also pointed out higher mortality rates of children born into polygamous families, the dangers of early sexualization of girls, gender inequality, and the problem of so-called lost boys – young men turfed out of polygamous communities as a result of competition for young brides.

Bauman acknowledged the infringement of the law on rights guaranteed by the charter, but concludes those limits are reasonable given the prohibition’s objectives. But he suggests a change to the way the law is interpreted as it applies to children between ages 12 and 17 who marry into polygamy.

He said the law would criminalize children – amounting to a serious impairment of "young persons’ liberty interests."

Bauman spent several months hearing testimony and legal arguments about whether the 121-year-old ban on multiple marriages is constitutional.

The landmark hearings, which wrapped up in April, focused on the polygamous community of Bountiful, but the ruling is expected to have implications for polygamists in the Muslim community.

The constitutional test case was prompted by the failed prosecution of two men from Bountiful who were charged in 2009 with practising polygamy.

The B.C. government then asked the court to rule whether Canada's polygamy laws violated the Constitution and Charter of Rights and Freedoms.

Residents of Bountiful follow the Fundamentalist Church of Jesus Christ of Latter-Day Saints, or FLDS, which, unlike the mainstream Mormon church, holds polygamy as a tenet of the faith.

The court heard evidence that teenage girls in Bountiful were taken across the Canada-U.S. border to be married, prompting RCMP in January to announce a renewed criminal investigation into the community of about 1,000 people in southeastern B.C.

The provincial and federal governments have pointed to the inability to lay charges, under the polygamy law or any other, as a reason to uphold the multiple marriage ban.

The polygamy law, the governments said, is the only way to prevent and punish such crimes in a closed religious community that shuns outside scrutiny and where the plural wives themselves are unwilling to co-operate with police.

Challengers argued the Criminal Code covers offences such as sexual exploitation, human trafficking and kidnapping. Polygamy, they claim, isn't the issue.