The federal prohibition on polygamy is a relic from another time that imposes Christianity on all Canadians and violates their right to religious freedom, says a lawyer arguing against the law.

Tim Dickson, a lawyer appointed to oppose the governments' position at the landmark constitutional case in B.C., said Monday that the law was originally motivated by fears of Mormon immigrants flooding into Canada to practise polygamy.

In fact, the 1890 law specifically referred to Mormon polygamy, known as spiritual or plural marriage, for more than half a century until the wording was changed in the 1950s to remove the reference.

"Faced with the emergence of Mormon religious beliefs that ran counter to mainstream Christianity, Parliament responded by mandating the conjugal form recognized in Christendom," said Dickson as the case entered its final week of closing arguments.

'The notion that this law was passed to protect women and girls is just not supported by the legislative history.'—Lawyer Tim Dickson

"Earlier versions of the law overtly targeted and discriminated against Mormons, and the law as a whole takes the Christian monogamous view of marriage and imposes it on all Canadians, regardless of their beliefs, regardless of their individual circumstances, and it backs up that Christian standard with penal consequences."

The mainstream Mormon church officially renounced multiple marriage around the same time anti-polygamy laws were enacted in Canada and the U.S.

But that hasn't stopped self-described fundamentalist Mormons in the U.S. and Canada, including residents of the small commune of Bountiful, B.C., from continuing to practise polygamy. It was the failed prosecution of two men from Bountiful that prompted the ongoing constitutional hearings.

Dickson said the Charter of Rights and Freedoms offers two protections regarding religion: laws cannot have a strictly religious purpose, and they can't actively discriminate against people of faith because of their religious practices.

He said it does both.

Even if the law was passed today, under the guise of protecting women and children, Dickson said it would still be unconstitutional.

He argued it prevents groups such as fundamentalist Mormons, as well as polygamous Muslims and Wiccans from fulfilling their religious beliefs, even in cases in which the marriages themselves aren't hurting anyone.

"That blunt, blanket approach is a relic of 1890 and it has no place in our modern, post-charter society," said Dickson.

"The notion that this law was passed to protect women and girls is just not supported by the legislative history or by the text of the law itself."

Many are happily polygamous

The federal and provincial governments have argued western societies have banned polygamy since Roman times — long before Christianity — and the law was always intended to protect women and children.

Dickson pointed to fundamentalist Mormons who testified in January, including several women from Bountiful, who told the court they were happy and freely chose to live as one of many wives.

The court also received written affidavits from so-called polyamorists, who live in multi-partner relationships that aren't connected to a religion.

All of them, said Dickson, are targeted by the current law.

"These witnesses, their polygamist relationships are profoundly important, profoundly beneficial," said Dickson.

"They help them fulfil themselves, and in this way those relationships are every bit as beneficial to individuals and to society as are monogamous relationships."

He also noted the law states that "every one" who practices polygamy is guilty, which he said would also include women and children in abusive polygamous relationships. That reality undermines the argument that the law is designed to protect wives and children, he said.

The governments have argued there is a long list of harms that are inherently caused by polygamy, including sexual abuse, child brides, teen pregnancy and human trafficking. Those problems, the government argues, justify a blanket ban, even if it's possible to find cases in which polygamous marriages aren't dangerous.

They also say those harms outweigh any claim to religious freedom.

The B.C. government asked the court to examine the Criminal Code section outlawing multiple marriage after polygamy charges against two competing bishops in Bountiful were thrown out.

Winston Blackmore and James Oler, who lead divided factions within Bountiful, were each charged in 2009, but the charges were later stayed over a technical legal issue.

The court has heard Blackmore has as many as 25 wives and Oler has at least five.