Texas Attorney General Ken Paxton is challenging the Obama administration on a new rule that would allow married same-sex couples to be eligible for the Family & Medical Leave Act, even in states that don’t recognize their unions.

In a statement on Wednesday, Paxton said the lawsuit is “about defending the sovereignty of our state,” which has a state constitutional amendment banning same-sex marriage.

“The newly revised definition of ‘spouse’ under the FMLA is in direct violation of state and federal laws and the U.S. Constitution,” Paxton said. “Texans have clearly defined the institution of marriage in our state, and attempts by the Obama Administration to disregard the will of our citizens through the use of new federal rules is unconstitutional and an affront to the foundations of federalism.”

According to the news statement, Paxton is also advising Texas employers to defy the Obama administration and follow state law, not the federal rule, as it pertains to FMLA.

After the Supreme Court ruled against the Defense of Marriage Act in 2013, the Obama administration sought to extend the federal benefits of marriage to the furthest extent possible under the law.

But FMLA by regulation looked to the state of residence, not the state of celebration, to determine whether a couple is married, so for a time married same-sex couples in non-marriage equality states were ineligible for benefits under that law, which enables an individual to take time off from work to care for a spouse.

The new rule, made final by the Labor Department last month and set to take effect March 27, changes the regulatory framework to ensure these benefits are available to married same-sex couples regardless of their state of residence.

The 23-page complaint Paxton filed before the U.S. District Court for the Northern District alleges the new rule is unconstitutional on the basis that it violates the Full Faith & Credit Statute and the Supreme Court’s ruling against the Defense of Marriage Act. According to lawsuit, the DOMA decision allowed states to continue to define marriage as they see fit, although numerous courts have rejected this interpretation of the ruling.

“The Department’s Rule diminishes stability and predictability of marriage in Texas by forcing Texas employers to acknowledge same-sex unions as marriages to grant the spousal care benefit, while the federal full faith and credit statute upholds Texas’s right to disregard such unions according to Texas policy,” the complaint says.

Also cited in the lawsuit is potential harm to employers if the FMLA rule takes effect, including the State of Texas itself, which employs 310,000 individuals.

“Employers in Texas will be called upon to decide issues that the Supreme Court has not yet decided, and those employers do so without the benefit of briefing and oral arguments for the full presentation of the issues on both sides,” the complaint says.

The prayer for relief is a declaration from the court that the change to FMLA is unlawful under the Administrative Procedure Act; temporary relief in the form of a temporary restraining order enjoining the Obama administration from beginning to enforce the change on March 27; and a permanent injunction declaring the new rule invalid.

Even though the lawsuit was filed in Texas and based on that state’s prohibition on same-sex marriage, the prayer for relief would have the effect of barring the FMLA change from going into effect in not just Texas, but all 12 states that currently don’t recognize same-sex marriage.

Chuck Smith, executive director of Equality Texas, criticized the attorney general for undertaking the effort against the FMLA change when so many states at this time have marriage equality.

“Texans should ask AG Paxton why he is expending state resources trying to prevent the federal government from recognizing the marriages of its own federal employees,” Smith said. “The freedom to marry is now legal in 38 of 50 states. All federal employees should have equal access to the benefits afforded by the FMLA, including legally married same-sex couples regardless of where they currently reside.”

Because the lawsuit is based on Texas’ ban on same-sex marriage, the litigation would seem to be moot if the state’s constitutional amendment were struck down. A lawsuit challenging the ban is pending before the U.S. Fifth Circuit Court of Appeals, which seemed during oral arguments likely to rule against the prohibition on gay nuptials. A nationwide ruling from the U.S. Supreme Court in favor of same-sex marriage, as many observers are expecting in June, would also seem to make the lawsuit moot.