Protesters in North Carolina say a new state law prohibiting people from using bathrooms associated with their gender identity discriminates against the LGBT community. (Reuters)

When the city of Charlotte outlawed LGBT discrimination in February, civil rights groups knew that political retaliation was coming.

The blow landed last week. In a single day, the governor and legislature of North Carolina unveiled, deliberated, passed, and signed into law a bill that activists have described as the most extreme anti-LGBT measure in the country — forcing transgender people into bathrooms that differ from their gender identity and disabling cities from creating laws protecting LGBT people.

What happened in North Carolina may have been startling for its swiftness, but it was a classic countermove in the modern conflict over gay rights. When liberal cities enact laws to protect LGBT people, conservative state governments respond by preempting them.

North Carolina is now the third state in the last five years to ban local anti-discrimination ordinances after a city tried to protect LGBT people. This is a maneuver of questionable constitutionality.

“They jammed this through with virtually no notice,” says Shannon Minter, legal director of the National Center for Lesbian Rights. “Everything about this process stinks. It’s got all the hallmarks of a bill that’s based on animus.”

Arkansas lawmakers passed a similar law last year, after the city of Fayetteville sought to prohibit bosses, landlords, and shopkeepers from discriminating against LGBT people in a bill that was rescinded soon after. Tennessee’s legislature also passed a law in 2011, after Nashville and Davidson County cut ties with businesses that discriminated against LGBT workers.

Though North Carolina’s law goes the furthest — it limits what bathrooms transgender people can use — what these three measures have in common is that they were all engineered to test the limits of what the U.S. Constitution allows. The 14th Amendment promises equal protection under the law, meaning that governments can’t single out and punish groups of people for no good reason. But the Supreme Court has been consistently vague about what that promise means for LGBT people.

This latest controversy may finally clear some things up.

On Monday, the ACLU, Lambda Legal, and Equality North Carolina filed a lawsuit arguing that North Carolina's new law “violates the most basic guarantees of equal treatment and the U.S. Constitution." Legal experts say this will be a tough case to litigate, but if it proceeds, it has the potential to set a landmark precedent. It may force the Supreme Court to confront a question that for decades it has stubbornly refused to answer: What does the Constitution actually imply about gay rights?

[The twisted history of religious freedom laws and their resurrection as anti-LGBT strategy]

Religious freedom proposals are being weighed in nearly a dozen states after the Supreme Court legalized gay marriage. (Claritza Jimenez/The Washington Post)

What the North Carolina law says

The North Carolina bill has two parts. First, it requires public schools and agencies to segregate bathrooms by the biological sex on someone’s birth certificate. This provision has attracted the lion’s share of the attention so far because it is the first statewide law of its kind. Civil rights activists fear that by forcing trans women into men’s rooms, and forcing trans men into women’s room, the new law will put transgender people at risk of violence.

The second part of North Carolina’s bill prohibits any city or county from creating new anti-discrimination laws. It’s very similar to laws already on the books in Tennessee and Arkansas, all of which are carefully worded not to mention gay people at all. The impact of these laws is clear though. In North Carolina, for instance, the immediate effect will be to make LGBT discrimination legal again in Charlotte.

These anti-anti-discrimination laws share a famous common ancestor. In 1992, voters in Colorado approved a constitutional amendment prohibiting any agency, school district, or local government from protecting “homosexual, lesbian or bisexual” people. This invalidated the LGBT anti-discrimination ordinances in Denver, Aspen and Boulder. Those cities promptly sued the state, arguing that the measure violated the Equal Protection clause of the 14th Amendment.

That lawsuit, known as Romer v. Evans, reached the Supreme Court in late 1995 and resulted in a landmark victory for gay rights the next year. But everything happened in a very strange way.

The strange decision in Romer v. Evans

The Equal Protection clause of the 14th Amendment says that laws in the United States must apply equally to everyone. Of course most legislation fails to treat people equally — and that’s okay. There just needs to be a reason — a “rational basis” — even if it’s a flimsy one.

Laws discriminate by age all the time, for instance. If a state wanted to ban the sale of gummy snacks to people under the age of 16, that would be ludicrous, but probably legal. Lawyers could argue that children under 16 are at higher risk for choking on these candies. The justification doesn’t have to be all that convincing; it just has to be not crazy.

When laws discriminate against certain kinds of people, though, the courts become much more suspicious. Lawyers often speak of a three-tiered system. At the top are categories like race, national origin or religion. Laws that explicitly discriminate against race are practically impossible to justify and hardly ever survive judicial review. Even laws that do not mention race can be struck down if it can be proven that they were enacted with discriminatory intent.

To a lesser extent, the courts are also wary of laws that discriminate by sex. This middle tier of review is called “intermediate” or “heightened” scrutiny, and it’s a relatively recent development. In 1976, the Supreme Court struck down an Oklahoma law that allowed young women but not young men to buy certain kinds of weak beer. Oklahoma tried argue that young men were more likely to drive drunk, so they shouldn’t be allowed to buy beer until they were 21. But the court didn’t find that reason convincing enough for the law to stand.

On the other hand, the court has upheld other kinds of sex-based discrimination — it ruled in 1981 that the draft was legal even though the military only required men to register.

For everyone else, courts use the extremely lenient “rational basis” standard. Practically speaking, nearly any law can clear this low bar. In the words of New York University constitutional law professor Kenji Yoshino, this is essentially “a free pass for legislation.”

Laws that discriminate against sexual orientation tend to be judged at this lowest level of scrutiny. Courts generally don’t believe that gays and lesbians are a class of people who deserve special protection under the Constitution. For these reasons, it’s extremely hard to win a case just by saying that a law is unfair to LGBT people.

Except that’s exactly what happened in 1996, when the Supreme Court struck down Colorado’s anti-LGBT law in Romer v. Evans.

Civil rights groups had been hoping the court would recognize that sexual minorities, like racial or religious minorities, deserved extra protection under the Constitution beyond rational basis review. But the Supreme Court refused to elevate LGBT people. Instead, Justice Anthony Kennedy said that Colorado’s law failed even the flimsy rational basis standard.

“[Colorado’s] amendment seems inexplicable by anything but animus toward the class it affects; it lacks a rational relationship to legitimate state interests,”  Kennedy wrote in the majority opinion, which struck down the Colorado law with the unlikeliest of legal tools.

It was like a toy gun had suddenly spit out a real bullet.

LGBT rights in limbo

The Supreme Court has never really cleared up what it thinks about LGBT people. Not once has it said that sexual orientation is a suspect classification, like race or religion. But there seems to be a winking understanding that LGBT people do deserve some special consideration.

“Formally, the issue is somewhat up in the air,” says Katie Eyer, an associate professor at Rutgers who teaches anti-discrimination law.  “But I think most observers agree at this point that the federal courts and the Supreme Court in particular do give some level of meaningful scrutiny to laws that discriminate based on sexual orientation.”

Recent legal victories for gay rights have danced around this issue. In Lawrence v. Texas, the Supreme Court struck down anti-sodomy laws not because they discriminated against gay people, but because these laws intruded on the “realm of personal liberty.”

“The petitioners are entitled to respect for their private lives,” Kennedy wrote in the majority opinion. “The State cannot demean their existence or control their destiny by making their private sexual conduct a crime.”

In the gay marriage cases, United States v. Windsor and Obergefell v. Hodges, the court used hybrid reasoning that blended a number of concepts in the Constitution, among them the rights to liberty and equal protection under the law. But again, the opinions fell short of recognizing sexual orientation as a suspect class. Obergefell in particular has been criticized by legal scholars for being muddy and confusing.

“Justice Kennedy squandered an important opportunity to leave a more enduring gay rights legacy,” University of Washington law professor Peter Nicolas wrote of the the decision last year.

So while gay rights activists cheered the outcome of these marriage cases, the legal status of LGBT people remains in limbo. This is where the lawsuit in North Carolina comes in.

The trick in North Carolina’s anti-LGBT law

North Carolina’s law uses a trick pioneered in Tennessee. A few years ago, Tennessee lawmakers passed a funny-sounding bill called the “Equal Access to Intrastate Commerce Act.”

The official goal was to make the state more business-friendly by prohibiting cities from burdening companies with anti-discrimination ordinances. The implicit goal was to disarm Nashville and Davidson County’s new LGBT anti-discrimination ordinance. The law said that only the state could dictate what kinds of people deserved protection from discrimination — and LGBT were conspicuously left out.

Tennessee’s law is a spiritual twin to the Colorado law that the Supreme Court struck down in Romer v. Evans. But it’s different in a crucial way. Tennessee’s law doesn’t mention LGBT people at all. That's an intentional dodge.

In Romer v. Evans, the Supreme Court made a big deal over how Colorado had singled out gay people, by name, in a piece of legislation. But the language of the Tennessee law is completely neutral — essentially, it freezes discrimination law until the state says otherwise. In practice, of course, the law closes the door on LGBT people, who were starting to win anti-discrimination protections in some liberal Tennessee cities.

Civil rights groups hoped that courts would see through the subterfuge in the Tennessee law. They argued that the measure was clearly motivated by anti-gay animus, violating the Constitution’s Equal Protection clause. But a lawsuit against Tennessee failed; in 2014, an appeal court dismissed it on a technicality, ruling that the plaintiffs couldn’t prove they suffered any harm from the new law.

The big question remained unanswered. Would the Supreme Court finish what it started in Romer v. Evans?

The Court's unfinished business

For years, constitutional scholars have been puzzling over the Supreme Court’s strange stance on LGBT issues. One thing is clear: The court has repeatedly insisted that sexual orientation gets no special treatment under the Constitution’s promise of equal protection.

Theoretically, a law crafted to disadvantage LGBT people is constitutionally okay as long as a judge can imagine some reason for it. That’s the meaning of the “rational basis” standard. A law just has to be not crazy.

In Romer v. Evans, the Supreme Court said it was applying the rational basis standard, but it ignored plenty of eligible justifications for a blanket ban on LGBT protections — cost, religious deference and so on. In overturning Colorado’s law, the Supreme Court seemed to be overzealous.

Constitutional scholars even have a name for what the court was doing — they say that it was applying “rational basis with a bite.” Many view it as a signal that the court is ready to evolve on an issue.

The court did something very similar in the 1970s, when it started recognizing sex as a protected class. At first, the court took baby steps without explaining what it was doing, which confused many people. But after a few years, the court finally announced that it had actually changed its mind about what the Constitution says about laws that discriminate based on gender.

“The word on the street — or, in the case of lawyers and law professors, the word on the internet — is that Romer cannot mean what it says, but instead must be a way-station to declaring homosexuality a quasi-suspect classification like gender or illegitimacy,” legal scholars Daniel A. Farber and Suzanna Sherry wrote at the time of the Romer decision.

So does North Carolina’s law violate the Constitution?

The lawsuit in North Carolina urges courts to finally treat gender identity and sexual orientation as suspect or quasi-suspect classifications under the Equal Protection clause. This has long been a goal in the gay rights community. It would mean that politicians could no longer pass laws that target LGBT people without some serious explaining.

There are other claims in the lawsuit as well. The transgender bathroom provisions in North Carolina’s law may run afoul of Title IX, the federal law that prohibits sex discrimination in schools. According to the Department of Education’s interpretation of the law, Title IX also bans transgender discrimination, which the DOE considers a form of sex discrimination.

By forcing students to use the bathroom that matches their birth certificate instead of the bathroom that matches their gender identity, North Carolina may be jeopardizing over $4 billion dollars in education funding that it receives annually from the federal government. A similar lawsuit involving Title IX and transgender restrictions in Virginia is already before the 4th Circuit, whose jurisdiction includes North Carolina, so this issue could be decided first.

But the most thrilling outcome for LGBT activists would be a win on the constitutional arguments. It’s something of a long shot, as we've seen. For decades, gay rights groups have lobbied the Supreme Court to recognize that LGBT people are a historically persecuted group that deserve heightened protections under the Constitution’s promise of equal treatment under the law. (An alternate argument is LGBT people should already receive heightened protections because LGBT discrimination is a form of sex discrimination, and sex is already a quasi-suspect class.)

Versions of these arguments have come before the Supreme Court in the famous sodomy cases Bowers v. Hardwick (1986) and Lawrence v. Texas (2003) as well as the in gay marriage cases, United States v. Windsor (2013) and Obergefell v. Hodges (2015) — but never with much success.

The closest the court ever came to sympathizing with the plea for equal protection was in Romer v. Evans, when it struck down Colorado’s anti-LGBT law. But even then, it would not admit that it was applying heightened scrutiny. It was a strange half-measure. (This situation has been in limbo for so long that some legal scholars wonder if the entire scheme of tiered scrutiny — one of the first concepts that’s taught in constitutional law — is becoming obsolete.)

North Carolina’s new law is an evolved cousin of Colorado’s law. Both were created to stymie local LGBT protections, but Colorado’s law singled out gay people by name, while North Carolina’s law is more coy. So if the Supreme Court wants to strike down North Carolina’s law for disadvantaging gay people, it will have to use more firepower than it did in Romer v. Evans. It may finally have to come out and say what it has been hinting at for years.

If gender identity and sexual orientation became recognized as a protected classes, deserving of heightened judicial scrutiny, the repercussions would be enormous. Not only would it inflame the struggle between religious rights and gay rights, but it would call into question many of the anti-LGBT bills being considered around the nation. In recent years, particularly since the legal victories for same-sex marriage, conservative groups have focused their attention on state legislatures, where they lobby for restrictions on the rights of LGBT people. Heightened judicial scrutiny would tank many of those measures.

The North Carolina lawsuit has a long road ahead of it. But it has the makings of a milestone case. If it ever reaches the Supreme Court, it will force the justices to tackle an issue that they have repeatedly hemmed and hawed over.

The court has ruled that bans on sodomy are unconstitutional. It has ruled that bans on same-sex marriage are unconstitutional, too. But is it constitutional for a law to discriminate against LGBT people? The Supreme Court has been mysterious on that subject for a very long time.