FRANKFORT, Ky. — Kentucky governor Steve Beshear says in a new legal brief that same-sex couples should not be allowed to marry because they cannot “naturally procreate,” and the state has an interest in ensuring that they do.

In appealing a federal judge’s ruling that the state’s same-sex marriage ban violates the constitutional guarantee of equal protection, Beshear’s counsel — attorney Leigh Gross Latherow — says Kentucky has an interest in maintaining birth rates, which, if allowed to fall, can induce economic crises because of the reduced demand for good and services and the reduction of the work force.

Beshear hired a private law firm to defend the ban after state Attorney General Jack Conway refused to “defend discrimination.”

In the brief, Latherow cites recent dips in the economies of Germany and Japan tied to declines in their birth rates, reports the Courier Journal.

“Procreation is vital to the continuation of the human race and only man-woman couples can naturally procreate,” the brief said.

Attorneys for the plaintiffs in the case said Beshear’s logic is “ridiculous.” Many heterosexual marriages don’t produce children, they said, and allowing gays and lesbians to marry will not discourage heterosexual Kentuckians from having babies in or out of wedlock.

“This is not a rational basis for state interest in who can marry,” said attorney Laura Landenwich, who represents the same-sex couples.

“You don’t, when you apply for a marriage license, have to check a box stating that you will procreate. Marriage is about a lot of things — love, sharing, responsibility. Children can be a big part of that, but they aren’t present in every marriage,” said Landenwich.

On that note, the state’s appeal says that just because “man-woman couples who are infertile or incapable of naturally procreating are allowed to marry does not nullify the rational basis for a man-woman marriage classification.”

The state claims that laws don’t have to be perfectly symmetrical to past muster under the equal-protection clause.

Chris Hartman, director of the Kentucky Fairness Campaign says the the “procreation” argument is one that was used a generation ago.

“It’s an embarrassing and ludicrous regurgitation of some really archaic talking points,” said Hartman. “It’s shocking that the governor would allow the legal team to use them.”

In February, U.S. District Judge John G. Heyburn II struck down Kentucky’s law banning the recognition of same-sex marriages performed out-of-state, saying the state had offered no rational basis for treating gay and lesbian couple’s differently.

The decision came in lawsuits brought by four same-sex couples seeking to force the state to recognize their out-of-state marriages.

The ruling did not deal with the question of whether the state can be required to issue marriage licenses to same-sex couples; that issue wasn’t brought up in the lawsuits.

Heyburn has issued a stay on his order until the U.S. Court of Appeals for the Sixth Circuit in Cincinnati either rules on the merits of the case or orders the stay lifted.

Follow this case: Bourke v. Beshear.