The Supreme Court is weighing how much employers must do to accommodate pregnant workers under a federal law aimed at combating discrimination against them.

Questions from several justices during arguments Wednesday suggested the court could be searching for a middle ground between United Parcel Service and former driver Peggy Young.

UPS refused to give Young temporary light-duty work so she could avoid lifting heavy packages after she became pregnant in 2006.

Young was in the courtroom Wednesday to hear the justices talk about employers' responsibilities under the 36-year-old Pregnancy Discrimination Act. The outcome of the case could affect many women who want to continue working throughout their pregnancies.

Justices Ruth Bader Ginsburg and Elena Kagan pressed UPS lawyer Caitlin Halligan over the Atlanta-based package delivery company's refusal to find a temporary assignment for Young.

The UPS policy "accommodates some workers but puts all pregnant women on one side of the line," Kagan said.

But in defending the company's actions, Halligan said UPS did not provide light-duty work to any employees unless they were injured on the job or had a condition that was covered by the Americans With Disabilities Act.

UPS has since changed its policy and says it will voluntarily offer pregnant women light duty starting in January.

Halligan noted that nine states now have laws that require an accommodation for pregnant workers.

More than 120 Democrats are backing legislation that would change the federal law to make explicit the requirement to accommodate pregnant women. Pennsylvania Sen. Bob Casey said the bill is modeled after the landmark disabilities law. "It would make sure that pregnant workers have the same measure of protection," Casey said before the start of a rally outside the court in support of Young.

The Obama administration and an unusual array of liberal and conservative interest groups are supporting Young, who lives with her 7-year-old daughter, Triniti, in Lorton, Virginia.

Since the justices agreed in July to hear the case, the Equal Employment Opportunity Commission has updated guidance to employers to make clear that they should accommodate people in Young's situation. Yet the U.S. Postal Service, an independent federal agency, maintains the practice that UPS has now abandoned, UPS said in court papers. The Postal Service declined to comment.

Solicitor General Donald Verrilli acknowledged in court Wednesday that the Justice Department has previously defended the Postal Service in similar lawsuits. Verrilli pointed to the recent EEOC change to justify the administration's shift in legal strategy.

Young's dispute with UPS arose after she gave her supervisor a doctor's note recommending that she not lift packages heavier than 20 pounds. Young said she dealt almost exclusively with overnight letters, but UPS said its drivers must be able to lift packages weighing up to 70 pounds. Young left the company in 2009.

The U.S. Chamber of Commerce is among those on UPS' side. The chamber says many of its members do provide additional benefits to pregnant workers, but it says policies at thousands of companies would be upended if the court were to rule for Young. Lower federal courts have rejected her claim.

A decision in Young v. UPS, 12-1226, is expected by late June.