The law, which came into effect in March, requires transgender people to use public bathrooms corresponding to the sex on their birth certificate.

North Carolina Governor Pat McCrory and the state's secretary of public safety sued Vanita Gupta, the department's senior civil rights lawyer, as well as Attorney General Loretta Lynch for their "radical reinterpretation" of federal civil rights law in federal district court in North Carolina.

The Department of Justice has said the law violates federal civil rights laws, arguing that existing federal civil rights protections that ban sex discrimination in the workplace and education also apply to transgender people.

The battle plays out along one of the several fronts in the US's so-called "culture wars," which - to simplify - pit a more traditional interpretation of societal mores against a more open attitude, running from abortion, to IVF and gay marriage, amongs many others.

The resentment in North Carolina is also associated with a political battle over federal reach into states' internal affairs, which tends to become heightened in an election year.

Things fall apart; the center cannot hold

Gupta sent three letters to North Carolina officials last week, saying the law was a civil rights violation.

The agency focused particularly on provisions requiring transgender people to use public restrooms matching their biological sex. The department says a lawsuit against the state is possible.

North Carolina in return has accused the agency of "baseless and blatant overreach."

If the state does not rescind implementation of the statute Monday it could face a federal lawsuit.

McCrory told Fox News Sunday he had asked the department to extend the Monday deadline, but was told that he could only have the extension if he would admit that the law was discriminatory. McCrory said that Obama administration officials are "acting like bullies."

"I'm not going to publicly announce that something discriminates, which is agreeing with their letter," he said in the interview.

The department declined to say whether it would take legal action if the state stands by the law. The letters suggest it is willing to do so, and this would be a potentially costly court fight.

Attitudes towards transgender people in the US

Americans tend to oppose laws that would require transgender people to use facilities that correspond with their gender at birth rather than their gender identity. A new CNN/ORC Poll said that 57% opposed laws requiring transgender individuals to use facilities that do not match their gender identity, 38% support such laws.

jbh/kms (Reuters, AP)