In a unanimous decision, the justices rejected a fair-pay lawsuit brought by warehouse workers in Nevada who package and ship products for Amazon.
The workers argued that they deserved extra pay because they had to spend as much as 25 minutes at the end of each day going through a security screening designed to prevent thefts.
Federal law says employers must pay workers a minimum wage and for overtime, but only for the time they are engaged in the "principal activity" of their job, not for the time of coming and going to their work site.
But the U.S. 9th Circuit Court of Appeals in San Francisco ruled for the Nevada warehouse workers on the grounds they were required to stand in line for the security screening. This added time to their workday, and it was done for the benefit of the employer, the appeals court said last year.
That decision triggered several class-action lawsuits brought by workers seeking back pay from Amazon, Apple Inc., CVS Health Corp. and other retailers that rely on warehouses and distributors.
But the Supreme Court reversed the 9th Circuit's ruling. Federal law covers only the "productive work that the employee is employed to perform," Justice Clarence Thomas said in the case of Integrity Staffing Solutions vs. Busk.
"Integrity Staffing did not employ its workers to undergo security screenings, but to retrieve products from warehouse shelves and package those products for shipment to Amazon customers."
The workers need not be paid, Thomas said, because their principal work does not include "the employees' time spent waiting to undergo ... security screenings."
Earlier this year, the high court also said federal law does not require paying workers for the time they spend putting on or taking off special clothing.