Thin edge of the wedge?

From Canada.com

Just weeks before it introduces divisive same-sex marriage legislation, the federal government has launched an urgent study into the legal and social ramifications of polygamy. Critics say the study
underscores a deep concern in the Martin government that legalized homosexual marriage may lead to constitutional challenges from minority groups who claim polygamy as a religious right.
It also suggests that the government is suspicious that multi-marriage is more commonplace in Canada than widely realized. Polygamy, outlawed in Canada but accepted and practised in many countries, typically means a man having several wives at the same time. "In order to best prepare for possible debate surrounding Canada's polygamy policy, critical research is needed," says a Status of Women Canada document. "It is vital that researchers explore the impacts of polygamy on women and children and gender equality as well as the challenges that polygamy presents to society."
Conservative party justice critic Vic Toews says there is a direct link between the Status of Women concern and the same-sex marriage legislation due to be introduced by the government in February.
"This government understands it has a problem on its hands," said Mr. Toews, a former Manitoba
constitutional lawyer. "What they are looking for is evidence to demonstrate that polygamy is inconsistent with Charter and Canadian values. If I was a lawyer prosecuting a polygamist that's the type of evidence I would be looking for."
Sayd Mumtaz Ali, president of the Canadian Society of Muslims, said he opposes same-sex marriage but said if it is legalized in Canada, polygamists would also be within their rights to challenge for their choice of family life to be legalized. "This is a liberally minded country with regards to equal rights," said Mr. Ali. "And literally millions live common law." Multiple marriage is legal in most Muslim countries, he said, but a Muslim man who takes more than one wife must prove to a court that he is capable of treating them all equally. He said he knows of some "but not too many" Muslims who live in
Canada with more than one wife but knows of no situation where the wives are unwilling, or unhappy, participants in the arrangement. But Mr. Ali said he has not detected any significant support among Muslims for a constitutional challenge. "To my knowledge there is no plan to push for this,' he said.
But when same-sex marriage becomes legal, the door will open to more Charter challenges, said Conservative critic Mr. Toews. "Once you change the definition of marriage from one man and one woman and you move to two persons," he said, "what then is the distinction between two persons, or three or more persons? If I was a lawyer defending polygamists, I'd say 'hey this is a constitutional
right, a freedom of religion.' Why can't freedom of religion trump this new definition of marriage?"