Mississippi’s HB 1523 has been called the “worst anti-LGBT law in America.” Now, after the 5th Circuit upheld the law last Thursday, it could finally go into effect.

Susan Sommer, director of constitutional litigation for the LGBT advocacy organization Lambda Legal, says it’s only a taste of challenges to come in a post-Obergefell country, and describes the law as a 'test balloon'.

HB 1523, signed by Mississippi Gov. Phil Bryant in April of last year but prevented from going into effect by a June 2016 injunction in the case Baker v. Bryant, grants broad permission to discriminate against LGBT people, ostensibly to protect the “free exercise of religious beliefs.”

It does so by literally writing anti-LGBT “religious beliefs” and “moral convictions” into state law, namely the beliefs that “marriage is or should be recognized as the union of one man and one woman” and that “male (man) or female (woman) refer to an individual’s immutable biological sex as objectively determined by anatomy and genetics at time of birth.”

The measure also creates room to discriminate against people who engage in premarital sex—in other words, almost everyone.

The law would not only grant religious organizations freedom to discriminate based on these beliefs, it also applies to individuals and state employees. Among many other things, it would expressly allow people to refuse to provide services for a same-sex wedding, allow business owners to adopt anti-transgender restroom policies, and allow state employees to recuse themselves from granting marriage licenses to same-sex couples.

It is, in Sommer’s estimation, a “particularly virulent example” of the anti-LGBT backlash that Lambda Legal has been witnessing since 2015’s Obergefell v. Hodges—a law that refuses a more careful “balancing” of religious freedom and equal protection.

“This law doesn’t do that at all,” she told The Daily Beast. “It creates this absolute right of anybody invoking so much as a religious belief—or even just a moral conviction—against the marriage of same-sex couples, or against transgender people, and gives them a completely free pass no matter how much of a hardship they’re inflicting.”

Lambda Legal joined local civil rights attorneys in Baker v. Bryant in December 2016 and helped argue in favor of the injunction in April of this year on behalf of 13 plaintiffs: 12 individuals and one LGBT-affirming church. Last Thursday, however, the 5th Circuit Court of Appeals reversed the June 2016 injunction, with three judges ruling that “the plaintiffs have not shown an injury-in-fact caused by HB 1523 that would empower the district court or this court to rule on its constitutionality.”

“I was very disappointed,” recalled Sommer. “I was not completely shocked though having defended the argument with my co-counsel.”

Gov. Bryant celebrated the reversal of the injunction in a statement, saying, “As I have said all along, the legislation is not meant to discriminate against anyone, but simply prevents government interference with the constitutional right to exercise sincerely held religious beliefs.” Spokespeople for Bryant did not immediately respond to a request for further comment on Monday.

Sommer told The Daily Beast that Lambda Legal and their co-counsel in Baker v. Bryant plan to file a petition for an en banc hearing before the full 5th Circuit Court of Appeals before the law can go into effect.

Contrary to last week’s reports, HB 1523 has not gone into effect just yet; as the Associated Press noted, that timing will “depend on the outcome of those appeals.” The 5th Circuit will first have to decide whether or not to grant the en banc request.

So far, the Mississippi law has been widely criticized by business leaders, especially in the tech industry. A handful of states, including California and New York, have banned nonessential government employee travel to Mississippi as well. But compared to the widespread public outrage directed at the Indiana state government in 2015 over their own “religious freedom” law, Mississippi’s has maintained a lower profile.

Whether that’s due to a distracting news cycle or the fact, as Sommer noted, that Mississippi is less of a “center of commerce in America” relative to Indiana, is unclear.

But as Sommer’s “test balloon” analogy makes clear, what’s happening in Mississippi will by no means stay in Mississippi. Other states have been testing the Obergefell ruling on same-sex marriage, with some prominent legal challenges only now rising to the Supreme Court level.

For example, Arkansas discovered on Monday that the Supreme Court would not abide a state law requiring same-sex couples to get a court order for both parents to be listed on their child’s birth certificate.

The Supreme Court also announced Monday it would hear the potentially precedent-setting case of a Colorado man who refused to bake a cake for a gay couple—a case that would have direct implications for laws like HB 1523.

But now, it’s the Arkansas ruling that’s giving Sommer hope for Mississippi.

“I think that [HB 1523] is an effort to deny same-sex couples equality and equal treatment, and the Supreme Court ruling today help sends a message that laws like Mississippi’s will not pass muster,” she said.