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 certificate.
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 administration's policy argue that it marks a significant change to settled law which 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.
The guidance is non-binding, but school systems could lose millions of dollars in federal aid if they fail to follow it.