I was always troubled by the definition of marriage that most states were passing that said that marriage only the marriage of one man and one woman would be valid or recognized by a state. The reason being that the definition still opens the door for polygamy, because technically speaking couldn't you argue that polygamy is only the relationship between one man and one woman. After all, the woman isn't married to the other wives, just the one husband. So polygamy is really a case in which one man has many separate marriages, but each marriage is only between one man and one woman. The definition never actually says that each individual may only contract one valid marriage at a time.
That is an excellent point. That definition has been used to defend heterosexual marriage by pointing out marriage as a cultural norm is the binding of one man to one woman even in cultures which support multiple simultaneous marriages. The entire group does not engage in a group marriage simultaneously, and if one of the wives dies or is divorced the other marriages are unaffected.
However, it begs the question. If civil marriage in the United States is not the legal binding of one man to one woman at one time, then what is the definition? The answer is, there is none. The judge found in today's society, restrictions on marriage were based only in religion and moral norms, not in legally defensible arguments. But he did not create a definition.
Since the case in California shot down not only Prop 8, but the very idea of restricting marriage via a definition, it has to have created a legal precedent to allow challenges.
Homosexual marriage is not recognized in the Federal tax code. All civil marriage is based on state laws. So there is no reason a state could not legalize polygamy, it would just mean if all spouses worked one wife could file jointly, and the remainder if they earned money would file as an unmarried individual.
So what is to prevent a polygamist from suing the state of California under an equal protection argument citing the judge's Prop 8 decision? Likewise, since this was a federal judge, deciding on federal constitutional grounds, what is to keep gays from any state from suing on similar grounds? What is to keep polygamist fundamentalists Mormon sects in Utah from suing Utah, or polygamist Muslims in Dearborn from suing Michigan?
I wonder if Ted Olson will take up the case for the fundamentalist LDS members who have been charged or convicted of bigamy.