Eleven U.S. states are suing the Obama administration over guidelines covering which school bathrooms transgender students can use.
The federal guidelines recommend that public schools let students use the bathrooms of the gender with which they identify, instead of what is on their birth certificates.
The lawsuit by 11 states, led by Texas, accuses the Obama administration of conspiring to turn schools into "laboratories for a massive social experiment, flouting the democratic process and running roughshod over commonsense policies protecting children and basic privacy rights."
Neither the White House nor the Justice Department has commented on the lawsuit.
Critics of the adminstration's policy argue that it marks a significant change to settled law that should be left up to Congress, not the White House. The Justice Department has rejected that argument, saying that federal civil rights laws, which bar discrimination on the basis of sex, provide the legal foundation for the department's guidance.
When announcing the guidelines this month, Attorney General Loretta Lynch said, "There is no room in our schools for discrimination."
The department's guidelines say a school "must not treat a transgender student differently from the way it treats other students of the same gender identity." The guidance is nonbinding, but school systems could lose millions of dollars in federal aid if they fail to follow it.
Texas Attorney General Ken Paxton said Wednesday that the Texas lawsuit was aimed at protecting a school district that has crafted a bathroom policy at odds with the Justice Department regulations, setting it up for possible retribution.
"We're taking this action to protect Harrold Independent School District, which on Monday night fulfilled a responsibility to their community by adopting a bathroom policy that puts the safety of their students first," he told reporters at a news conference announcing the lawsuit.
That legal rationale is similar to the argument made by North Carolina lawmakers who passed a law restricting access to restrooms, locker rooms and changing rooms, in part to protect against sexual assaults.
LGBT rights activists say they also care about safety and privacy, but that the concerns about the bathroom issue are overblown and end up further stigmatizing or perpetuating violence against transgender people.
Jay Brown, director of communications at the Human Rights Council, told VOA this week that people on all sides care about safety and privacy.
"There's not been a single increase of incidences in any bad behavior in bathrooms in any of the places where positive nondiscrimination laws have been passed," he said.
Wednesday's lawsuit opened a second legal challenge to the Obama administration's bathroom guidance. This month, the Justice Department and North Carolina sued each other over the state's new law curbing restroom access for transgender people.
VOA's William Gallo contributed to this report.