Employers can no longer refuse workplace accommodations to most pregnant employees if they offer similar accommodations to other non-pregnant employees, the U.S. Supreme Court ruled Wednesday.

The 6-3 decision had Chief Justice John Roberts and Justice Samuel Alito join the court’s liberal justices in ruling in favor of Peggy Young, a former UPS worker who was forced off the job when she became pregnant and was prescribed a lifting restriction by her doctor.

UPS denied her request, citing the company’s “pregnancy-blind” policy that refused workplace accommodations such as light-duty assignments to any employee unless they were injured on the job, qualified as disabled under the Americans With Disabilities Act, or lost their federal driver’s certificate. Because Young’s circumstance did not fit into any of those categories, UPS officials said they would not accommodate her request.

Young was forced to take unpaid leave, which meant a loss of her health insurance during her pregnancy and delivery.

Young returned to work after the birth of her baby and sued UPS under the 1978 Pregnancy Discrimination Act (PDA), a law passed in response to a 1976 Supreme Court decision that ruled pregnancy discrimination is not a form of sex discrimination. The PDA requires that employers treat “women affected by pregnancy” the same as “other persons not so affected but similar in their ability or inability to work.”

Young and her attorneys argued that because UPS granted light-duty job assignments to workers who were “similar” to Young in their “inability” to perform all job functions, it violated the PDA by refusing to grant the same accommodation to her.

Young lost at both the trial court and the Fourth Circuit Court of Appeals, which ruled that because UPS’s policy was “pregnancy-blind” and didn’t specifically state a bias against pregnant workers, the policy was not discriminatory. The Roberts Court on Wednesday disagreed, sending Young’s case back to the lower courts for a possible trial on UPS’s reasons for not accommodating Young.

Justice Stephen Breyer, writing for the majority, said Young could prevail in the lower courts if she can show that she was denied accommodations given to others similar in their ability to work, and that her employer’s policies impose a significant and unjustified burden on pregnant workers.

“Why, when the employer accommodated so many, could it not accommodate pregnant workers as well?” Breyer wrote.

Young, and presumably other employees, could meet that “significant and unjustified” burden by offering evidence that UPS accommodates “a large percentage of non-pregnant workers while failing to accommodate a large percentage of pregnant workers,” according to the Roberts Court.

Sam Bagenstos, who argued Young’s case before the Roberts Court in December, called the win significant for pregnant workers across the country.

“This is a big win for Peggy Young and other women in the workplace,” Bagenstos said in a call with reporters. “The Court recognized that employers can’t put pregnancy in a class by itself.”

Bagenstos explained that after Wednesday’s decision, employers need a particularly strong reason for not accommodating workers, and those reasons cannot be ordinary costs or convenience, which is one usually cited when employers deny requests like Young’s.

Sharon Fast Gustafson, who has represented Peggy Young since 2007, told reporters during the call that her client was very happy with the decision. “Peggy is thrilled. Her team is very pleased with this decision,” said Guftason. “For years, UPS has sent all of its pregnant workers who needed the slightest accommodation home from work without pay and benefits while accommodating many of its non-pregnant workers who needed similar accommodations. The Supreme Court has held that this is evidence upon which a jury can find that UPS was discriminating on the basis of pregnancy.”

It was not at all clear during oral arguments in December what path the justices would take to resolve the issue of what obligations employers have to accommodate pregnant workers, and I was not at all optimistic that the normally employee-hostile Roberts Court would side with Young, even in a case like this. But not only did the Roberts Court side with Young; two of its most anti-worker justices, Roberts and Alito, joined the majority.

“Today’s Supreme Court decision is an important victory for Peggy Young, and for many other pregnant workers, because it makes clear that employers can’t continue pushing pregnant workers out of their jobs while providing accommodations for other, non-pregnant workers,” Lenora Lapidus, director of the ACLU’s Women’s Rights Project, said in a call with reporters after the decision.

Indeed, despite fighting Young’s claims since 2007, UPS announced in January it was voluntarily changing its policy to now offer pregnant employees accommodations identical to the one it spent nearly a decade fighting. And since the PDA was first passed, at least nine states have stepped in and passed legislation that requires all employers to give pregnant workers reasonable accommodations unless those accommodations would impose an undue hardship on the employer.

Those state-level policy changes were partly responsible for UPS’s decision to stop refusing workplace pregnancy accommodations, according to the company in its brief to the Roberts Court.

Not surprisingly, Justices Antonin Scalia, Clarence Thomas, and Anthony Kennedy dissented.

Scalia, writing for the dissent, called the majority’s opinion “splendidly unconnected to the text” of the PDA, a pretty tame swipe considering Scalia characterized Young’s accommodation request as seeking a “most favored nation status” for pregnant workers during December’s oral arguments.

While Wednesday’s victory is significant, the opinion leaves room for employers to avoid addressing the ongoing and pervasive problem of pregnancy discrimination, and it should also come as no surprise that it’s Alito’s concurring opinion that most exploits any ambiguities for the benefit of employers.

In his concurring opinion, Alito wrote that an employer could deny a pregnant employee an accommodation it offers a non-employee of the basis of “neutral business grounds.” Just what is a “neutral business ground” for pushing a pregnant employee off the job? So far the Court has said it can’t be cost or convenience, but that’s as much guidance as justices have offered.

And when pregnant workers continue to lose their jobs over requesting accommodations like additional bathroom breaks, a stool to sit on while cashiering, or the ability to carry a water bottle with them, “neutral business grounds” still sounds like a gendered dog-whistle.

During oral arguments, Bagenstos told the justices that Young’s case, and the PDA, was really pretty simple.

“You have to treat pregnant workers as just as valued employees as anybody else,” Bagenstos said.

Wednesday’s opinion takes an important step in doing just that, and if employers are smart, they’ll do the same.