It took North Carolina lawmakers just a few hours to roll back anti-discrimination laws for gays, lesbians and transgender people.
The backlash may tie them up a lot longer.
As opponents began plotting a legal response, many of North Carolina's largest employers on Thursday said they were opposed to the new law, which prevents local governments from passing ordinances that prohibit discrimination in public places based on sexual orientation and gender identity.
"I don't think this is a law that a state like North Carolina, that wants to be business friendly, can really sustain," Chris Sgro, executive director of Equality NC, said Thursday.
The rapidly escalating dispute marks a new front in a nationwide battle over LGBT rights, where advocates have found allies in local governments and the Obama administration, only to run into conservative resistance. It's happened in Houston, Arkansas, Arizona, Indiana, Tennessee and South Dakota, and similar fights are brewing in Virginia and Georgia, where Disney, Marvel Studios and the NFL have threatened to boycott the state.
The North Carolina case is driven by an issue specific to transgender people: which bathrooms they can use.
Advocates say they should be free to use a bathroom that matches their chosen gender, even if it's not the one on their birth certificate.
But critics say those allowances would violate others' privacy and put women and girls at risk of being preyed upon by male sexual predators.
That argument fed backlash against an expanded anti-discrimination ordinance passed by the city of Charlotte last month — and prompted the Republican-led state legislature to call a special one-day session to head off the local measure's implementation.
The restrictive new bill, which went beyond the bathroom issue to bar more extensive local measures, passed easily on Wednesday, and Gov. Pat McCrory, who is running for re-election, signed it that night.
Civil rights groups are now exploring a myriad of possible legal challenges to the law. The Human Rights Campaign warned that the new measure opened the state up to challenges under Title IX, the federal law that prohibits sex discrimination in education.
The group noted that federal officialshave said barring students from restrooms that match their gender identity is prohibited under Title IX, and argued that a violation could put billions of dollars in federal education funding at risk.
The Title IX issue is what forced South Dakota's governor to veto a similar bill last month.
State lawmakers who've opposed LGBT anti-discrimination measures argue that the federal government is overreaching on an issue that should be up to states. But civil rights groups point out that many of those same lawmakers have chosen to preempt local governments that favor more anti-discrimination measures.
Gov. McCrory, a former Charlotte mayor, said as much in a statement about the city Wednesday night.
"While local municipalities have important priorities working to oversee police, fire, water and sewer, zoning, roads, and transit, the mayor and city council took action far out of its core responsibilities," McCrory said. "As a result, I have signed legislation passed by a bipartisan majority to stop this breach of basic privacy and etiquette which was to go into effect April 1."
Deborah Hellman, a University of Virginia School of Law professor who specializes in discrimination and equality, said the North Carolina law may be interpreted as violating the U.S. Constitution's equal protection clause.
The state, she said, is effectively telling Charlotte that despite its belief that gays, lesbians and transgender people need protection against discrimination, it can't doing anything for them. "The law effectively makes them worse off than anyone else, and that's a violation of equal protection," Hellman said.
She cited a 20-year-old U.S. Supreme Court ruling that found a Colorado measure that prevented gay people from getting protection from discrimination violated the equal protection clause. Though that ruling could be interpreted differently in the North Carolina case, the Supreme Court has since supported expanded rights for gays and lesbians, Hellman said.
Another potential challenge to the North Carolina law could come in the legislature itself.
That, opponents say, depends on the weight of the large corporations who do business in the state.
But a McCrory campaign spokesman told The Associated Press Thursday night that other businesses supported the new law. He didn't elaborate.
A little earlier, protesters gathered outside the governor's mansion in Raleigh. A few were arrested, local NBC affiliate WRAL reported.
The McCrory spokesman, Ricky Diaz, told the station that the governor stood by his decision.
"Standing with North Carolina parents who are worried about the privacy and safety of their children will always be a top priority for the governor, no matter the spin by the media, pundits or politically correct crowd," he said.
This article originally appeared on NBCNews.com.