NASHVILLE (AP) — A new law that's been criticized as discriminatory against same-sex couples actually does "nothing new at all," Tennessee's attorney general contends in a legal filing.

Attorney General Herbert Slatery made that argument last week in a motion to dismiss a lawsuit filed by four married lesbian couples expecting children through artificial insemination.

The law requires using the "natural and ordinary meaning" of words in state law. Gay rights groups have contended that the requirement offers a sneaky way to deny same-sex couples the legal rights and protections granted to a "husband," a "wife," a "father" or "mother."

In the lawsuit filed last month in Davidson County Chancery Court, the couples say they fear the law will be used to interpret gender-specific words literally so one parent won't be recognized.

The state's response says the new law only codifies a longstanding rule, and "in no way changes the law that has been in existence for decades."

The new law should be considered alongside a more-specific state law requiring gender-specific words to be interpreted as inclusive, the state's motion says. Previously, Slatery issued an opinion that said a judge would likely side with the state law requiring gender-inclusive interpretations.

The couples who filed the lawsuit acknowledge that the Tennessee Department of Health already recognizes the wife of a woman who gives birth through artificial insemination as the other parent, according to the motion.

The couples "assert nothing more than a theoretical 'fear' that the Department will act differently in the future and a desire for 'protection' from that hypothetical and contingent eventuality," the state's motion says.

After signing the measure into law last month, Republican Gov. Bill Haslam said it doesn't change the fact that a U.S. Supreme Court ruling makes same-sex marriage the law of the land.

The lead plaintiff in that landmark Supreme Court case, Jim Obergefell, had joined LGBT advocacy groups in calling for Haslam to veto it.

The law was pushed by the Family Action Council of Tennessee, which advocates for one-man, one-woman marriage.

Another bill this year explicitly cited "husband," ''wife," ''mother," and "father" as having natural and ordinary meanings based on the biological distinctions between men and women. That bill gained no traction. The measure that ultimately passed avoids those specifics, and merely states that any word undefined in state law must be used according to its "natural and ordinary meaning."

The state's motion also points out that in a divorce proceeding last month, a Knox County judge ruled that the wife of a woman who conceived a child through artificial insemination was a parent. That ruling came before the new law was signed.

The judge had initially ruled differently, saying in June 2016 that the wife had no parental rights because she did not meet the legal definition of "husband."

Dozens of conservative Tennessee lawmakers had tried to intervene in the case, but the judge rejected the request.