The ban prevents the polygamous from marrying their chosen partners just as the prohibition of same-sex marriage deprives gays of that freedom. Josh can't marry Zack; Michael can't marry Katie and Nicole. If the right to marry encompasses the former, why not the latter?
Gays argue, correctly, that they can't be expected to change their inborn sexual orientation to get married. But polygamists can assert that monogamy is impossible for them -- and, judging from the prevalence of sexual infidelity, for most people.
Nor does the polygamy ban solve any problems. Men can already have sex with multiple females, produce offspring with them and furnish them with financial support. Former NFL running back Travis Henry has nine children by nine different women.
Prohibiting polygamy does nothing to prevent such conduct. It just keeps people who want to do it responsibly from operating within an established legal framework.
That's why I would legalize polygamy as well as same-sex marriage. But it's one thing to believe those changes would make sound policy and entirely another to think that the Constitution requires either -- especially when California, which passed Proposition 8, has granted gay couples access to most of the rights afforded by marriage.
The decision may very well lead the Supreme Court to rule in favor of same-sex marriage. If so, it would be the most polarizing decision since Roe v. Wade in 1973, which we are still fighting about.
It would spark a furious backlash from Americans who, whatever their views about homosexuality, think such decisions belong with them and their elected representatives. It could even lead to a constitutional amendment overturning the decision.
Thanks to Judge Walker, the debate is no longer about whether gays deserve protection from the law, a debate they were steadily winning. It is more about whether democratic processes should be trusted to resolve the question. That's a debate they are likely to lose.