Carlos McKnight, 17, of Washington holds up a flag in support of same-sex marriage outside the U.S. Supreme Court in June 2015.  (Jacquelyn Martin/Associated Press)

On its face, the bill passed by the Tennessee legislature Thursday seems innocuous, if a little odd. The one-page measure requires that “undefined words” in state law “be given their natural and ordinary meaning.”

But LGBT rights groups say the measure is as insidious as it is simple, calling it a veiled attempt at undermining the 2015 Supreme Court decision that legalized same-sex marriage nationally.

The bill requires that words such as “husband,” “wife,” “mother” and “father” be interpreted “without forced or subtle construction that would limit or extend the meaning.” Groups advocating on behalf of the lesbian, gay, bisexual and transgender community say that means that parts of state law that refer to husbands and wives might not be interpreted to apply to same-sex spouses.

The bill’s sponsor, state Sen. John Stevens (R), has said the measure is not aimed at gay couples, according to the Times Free Press. “It absolutely is not,” Stevens said in response to questions from skeptical Democratic lawmakers, the newspaper reported.

But the measure follows a custody dispute last year involving a divorcing lesbian couple in the state, in which one member of the couple’s attorney asked that the judge substitute “spouse and spouse” for references in state law to “husband and wife.” A socially conservative group filed a motion to intervene in the case on behalf of 53 GOP lawmakers in the state who opposed the request.

Rights groups condemned the measure, which is headed to the desk of Gov. Bill Haslam (R), who has not said whether he will sign it. “The governor is deferred to the will of the legislature on this bill, but as he does with all legislation that is sent to his desk, he will review it in its final form before taking any action,” spokeswoman Jennifer Donnals said in an email.

The rights groups urged Haslam to reject the bill, which they said would exclude gay couples from state protections granted to heterosexual couples and conflict with the Supreme Court’s ruling in the same-sex marriage case.

“The passage of this legislation is an egregious and blatantly unconstitutional effort to take away the rights of same-sex couples,” Matt McTighe, executive director of Freedom for All Americans, said in a statement. “I urge Gov. Haslam to take a definitive stand for Tennessee’s LGBT community and veto this vindictive piece of legislation.”

The bill is the latest state effort that could undermine same-sex marriage rights. It comes less than a month after North Carolina lawmakers introduced legislation to outlaw gay unions in defiance of the Supreme Court. Republican leaders there have shelved the bill.