Utah has a perfectly good explanation for why it won't allow same-sex marriage: Gay couples can't make babies.

The Associated Press reports that the "procreation argument" is the state's main defense in a lawsuit against its laws against gay marriage. In a motion filed last week, three same-sex couples argued that the law in question—an amendment to the state constitution filed in 2004—is unconstitutional, discriminatory and violates gay people's "fundamental right" to choose a spouse. But Utah won't take such a reasonable argument lying down.

"Same-sex couples, who cannot procreate, do not promote the state’s interests in responsible procreation (regardless of whether they harm it)," the state argues in its own motion. No mention is made of opposite-sex couples who are infertile, choose not to have children or for some other reason do not procreate. Procreation is fundamental to the “age-old and still predominant” definition of marriage, says the state that claims to be the most “child-centric” in the union.

But if those arguments don't sway you, they've got another: the law simply can't be discriminatory, because it discriminates against men and women equally. "Neither a man nor a woman may marry a person of the same sex," reads the state's argument. So there.

The first hearing in the case is set for December 4.

[image via Getty]