WASHINGTON — Some warehouse workers who fill orders for Amazon.com customers say they spend up to 25 minutes after every shift waiting to pass through security checks to make sure they aren’t stealing from the online retailer. But they don’t get paid for the extra time.

The Supreme Court is hearing arguments today in a lawsuit filed by two former staffers at a Nevada warehouse who claim they should be compensated for time spent in security screenings under the Fair Labor Standards Act.

A ruling in favor of the plaintiffs could subject employers to billions of dollars in retroactive pay and increase costs for companies that have expanded security measures to curb employee theft. But it could also mean a slight boost in wages for millions of employees forced to spend extra time going through security.

Integrity Staffing Solutions, the independent contractor that provides staff for Amazon.com warehouses, claims no extra pay is required because the security clearances are unrelated to the workers’ core job duties.

The company requires departing workers to walk through a metal detector and remove wallets, keys and belts to make sure no merchandise has been stolen. The process takes time because hundreds of employees line up to leave at once, causing long lines.

A federal judge sided with the company, but the 9th U.S. Circuit Court of Appeals reversed the ruling. The appeals court said the clearance was necessary to the primary work performed by warehouse workers.