Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

The state of Texas has filed a last-minute suit asking a federal judge to block a rule requiring states to grant family medical leave protection to all married same-sex couples.

But the judge indicated Thursday that the suit may have been filed too late, meaning the first challenge to a major consequence of the Supreme Court's landmark ruling striking down the Defense of Marriage Act might never get to court.

The rule, which the Labor Department is scheduled to put into effect March 27, requires businesses, to observe the marriage laws of states where their employees were married — not where they currently live — in applying the Family and Medical Leave Act. In other words, under the rule, businesses in Texas and other states that don't recognize same-sex marriage are required to grant medical leave to same-sex couples married in other states that do recognize it.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

The Labor Department issued the regulation after the Supreme Court ruled in June 2013 in U.S. v. Windsor that the federal government's refusal to recognize same-sex marriages was unconstitutional.

In the suit, filed Wednesday in U.S. District Court in Wichita Falls, Texas Attorney General Ken Paxton argues that the Labor Department rule violates the sovereign immunity of states that don't recognize same-sex marriage, including Texas. It asks U.S. District Judge Reed O'Connor to issue a preliminary injunction declaring the rule illegal and a temporary restraining order blocking the rule from going into effect next week while the suit is litigated.

RELATED: Read the Full Lawsuit (PDF)

The rule "forces Texas to violate its own state laws by recognizing the laws of other states relating to same-sex marriages," the state argues, saying the rule "prevents implementation and enforcement of the will of the people of Texas."

The Labor Department had no comment Thursday night, saying it hadn't actually received a copy of the suit — a point that could lead to the suit's being thrown out.

In a sharply worded order Thursday, O'Connor scolded Texas for having filed the suit so close to the date the rule is to take effect, saying the state had left little time for arguments to be considered — and complaining that he had no proof that the U.S. was even aware that it was being sued.

RELATED: Read the Judge's Order (PDF)

O'Connor gave the state's lawyers until just 1 p.m. Friday (2 p.m. ET) to file proof that the U.S. attorney for north Texas had been given written notice.