The Supreme Court heard arguments yesterday related to the question of whether employers have to provide special accommodations to their pregnant employees. In 2009, a pregnant UPS driver named Peggy Young requested light-duty work, as recommended by her doctor. Instead, UPS put her on unpaid leave.

UPS had a policy offering light-duty work to workers injured on the job, as required by the Americans with Disability Act. When UPS put Young on unpaid leave, it insisted she was being treated no differently than any worker who became unable to do their job because of something that happened outside the workplace. 

What might be surprising here is that the law isn’t exactly clear on whether pregnant women must be accommodated in their jobs. Two lower courts have sided with UPS over Young, and other courts have ruled similarly. In one case, a court upheld an airline’s policy to refuse light-duty assignments to pregnant women. 

Now, there’s a chance for the Supreme Court to clarify a few unanswered issues surrounding the law at the center of this case—the Pregnancy Discrimination Act. 

When the Pregnancy Discriminatory Act passed Congress in 1978, it had one broad intended purpose: To ensure pregnant women receive equal treatment to work. As Supreme Court Justice Elena Kagan said during Wednesday arguments, the law “was supposed to be about removing stereotypes of pregnant women as marginal workers. It was supposed to be about ensuring that they wouldn't be unfairly excluded from the workplace.”

But the Pregnancy Discrimination Act “didn’t create affirmative policies,” says Ann O'Leary, the director of the Children and Families Program at the nonprofit Next Generation. “It didn’t say you get something more than other people as result of your being pregnant.” Likewise, the Family Medical Leave Act (FMLA) of 1993 made sure people don’t get fired for taking family or medical leave, but it does not require additional benefits, like paid maternity leave. (Workers are entitled to 12 weeks of unpaid leave under the FMLA.) Russia, Lithuania, China, Turkey, and others all offer paid leave while the U.S doesn't.

Part of this has to do with the way advocates, lawmakers, and the courts have historically given more attention to strict equality than to biology (for instance, the obvious biological difference that only women give birth). O'Leary argued in a paper for the Berkeley Journal of Employment and Labor Law that, despite good intentions, this particularly left low-income workers behind: “While the [Supreme] Court and equality feminists were focused on articulating a normative ideal of equality as strict equality between men and women, they failed to embrace the accommodation theory of equality, which suggests that equality must be reached by addressing both the real biological difference between men and women, based on the fact that only women can bear children, and the empirical reality that women are disproportionately responsible for caretaking.” 

If the Supreme Court decides in favor of Young, pregnant women may achieve certain protections, but other gaps will remain in the 36-year-old Pregnancy Discrimination Act. For now, attention is focused on the Supreme Court, but some politicians have pushed the issue in Congress as well: The Pregnant Workers Fairness Act is modeled on the Americans with Disabilities Act, and it would ensure pregnant women have reasonable alternatives to strenuous job functions like running, lifting, and constant standing. Young v. UPS shows just how necessary such a law is. In the Republican Congress, however the bill will almost certainly be sidelined.