A couple of days ago I asked the question that if SSM would lead to polygamy how would civil unions not lead to the same. Andrew Coyne offers an answer today in a single word, monogamy.
...If marriage is, legally speaking, about monogamy, and if there is no evidence to suggest that allowing homosexuals to wed will change that, then it follows that there is no reasonable grounds for preventing them from doing so. And as sexual orientation is, by previous jurisprudence, one of those personal traits the state may not discriminate against — or not without reasonable grounds — then the constitutional basis for the traditional definition of marriage falls away.
Even though I don't agree with the premise that marriage is just about monogamy, it is a well thought out argument nonetheless.
