Some critics of the Hatch amendment–which would reserve decisions about same-sex marriage to state legislatures–are saying that it would make it possible to legalize polygamy. I say they’re wrong. David Frum, in response, says that I’m right about 49 of the 50 states, but wrong about Utah. So he’s saying, in other words, that I’m 98% right.

His argument about Utah goes as follows: Congress admitted Utah to the Union on the condition that it ban polygamy, and that this ban could not be lifted without the consent of Congress. Passage of the Hatch amendment would constitute consent. So the Utah legislature could, in fact, legalize polygamy under the amendment when it could not have done so before.

Frum goes on to say that “it is probably very unlikely that Utah would be tempted to legalize polygamy.” Mormons now reject polygamy. But, he warns, others will take up the cause. He concludes, “And if there is any lesson of the same-sex marriage debate, it is this: Be prepared for the worst – because there will always be some judge out there who can be talked into it.” As I explained, however, the Hatch amendment would block judges–whether at the state or federal level–from imposing polygamy. If Frum’s argument about Utah is correct, then the Hatch amendment gives the Utah legislature a power to legalize polygamy which it will (by his own admission) almost surely not use. That’s all that this objection amounts to. Which isn’t much.