When social conservatives argue that legalizing same-sex marriage could lead to legalized polygamy, same-sex marriage advocates either laugh or sneer. It's a scare tactic, they say. It'll never happen.

 Last year, however, as Canada legalized same-sex marriage, Prime Minister Paul Martin commissioned a $150,000 study to debunk the polygamy argument. Big mistake: The study confirmed the scare tactic by recommending that Canada repeal its anti-polygamy law.

 It also suggested that a legal challenge to Canada's anti-polygamy laws would succeed. "Why criminalize behavior?" asked Martha Bailey, one of the study's three law-professor authors. "We don't criminalize adultery."

 Confession time: I am one of those who, for years, has argued that legalizing same-sex marriage would not open the door for polygamy. The limit for marriages would remain two, I argued. Two doesn't mean three or four.

 Wrong. In these politically correct times, do-gooders expand definitions until words -- or institutions -- lose all meaning. Marriage can mean what you want it to mean.

 And: If you don't prosecute all crimes in a category, you can't prosecute one.

 That's essentially what Bailey argued.

 The study recognized the "strong association between polygamy and gender inequality." Then the authors apparently decided that Canadian law should eliminate any legal unfairness -- in inherently unequal marriages.

 One Kuwaiti wife can't move to Canada to live with her husband and another wife. That's unfair to the wife and unfair to Muslims. The study noted, "The parties most likely to suffer from this rule are the left-behind wives." To eliminate that inequity, these professors are ready to provide legal cover for all polygamous (and polyandrous) marriages.

 "There's a logical extension to it," laughed Rob Stutzman, who worked on the Proposition 22 campaign in 2000, a measure that limited marriage in California to a union between a man and a woman. "If you accept the premise that marriage should be whatever relationships people want to enter into," he said, polygamy is legit.

 Brad Luna of the Human Rights Campaign, which supports same-sex marriage, finds any linkage of polygamy to same-sex marriage "offensive." He warned against reading too much into one Canadian study. In America, he said, "two people is the defining element in our system of government on contractual marriage." Continued...