The justices on Wednesday sided with former driver Peggy Young in throwing out lower court rulings that rejected her lawsuit.
The case concerned employers' responsibilities under the 37-year-old Pregnancy Discrimination Act. Atlanta-based UPS Inc. maintained that it obeyed the law because it provided light-work duty only in limited situations and did not single out pregnant women.
But the company changed its policy as of January and says it now tries to accommodate pregnant workers.
The vote was 6-3 in Young's favor. In ordering lower courts to look again at Young's claim, Justice Stephen Breyer said one consideration should be, "Why, when the employer accommodated so many, could it not accommodate pregnant women as well?"
UPS said did not provide light-duty work to any employees unless they were injured on the job, had a condition that was covered by the Americans With Disabilities Act or lost their federal certificate to drive a commercial vehicle.
Justice Antonin Scalia said in dissent that the majority waved "the Supreme Wand" to arrive at the outcome it preferred. Scalia said the law "does not prohibit denying pregnant women accommodations, or any other benefit for that matter, on the basis of an evenhanded policy." Justices Anthony Kennedy and Clarence Thomas joined the dissent.
The outcome reflects a "middle ground" that Justice Elena Kagan suggested during arguments in early December. Courts must now re-examine Young's case with a more accepting view of the discrimination claim. UPS and other employers facing similar suits still are able to argue their policies were legal because they were based on seniority or some other acceptable reason.
Young's dispute with UPS arose after she became pregnant through in-vitro fertilization and gave her supervisor a doctor's note recommending that she not lift packages heavier than 20 pounds. Young, now 43, 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 Virginia woman lost two rounds in lower courts.
UPS has since changed its policy and now says it will try to accommodate pregnant workers. Nine states also have adopted laws directing employers to do so.
In recent months, 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 said it has made no change in policy and maintains the practice that UPS has now abandoned.
Pregnant workers in situations similar to Young's also may have additional protections under 2008 amendments to the Americans with Disabilities Act. Young's pregnancy occurred before Congress changed the disabilities law.