Back in the 1940s, when the U.S. Supreme Court last spent a lot of time struggling with the question of what parts of a worker's day were included in the job for the purposes of getting an hourly wage, the cases tended to come out 5-4. Then, liberals inclined toward unions while moderates and conservatives preferred employers.
Times have changed. Tuesday, the Supreme Court issued a 9-0 decision that warehouse employees who spend their days fulfilling Amazon orders won't be paid for mandatory end of the day screening designed to check if they've stolen anything from the shelves. To do so, the court interpreted the 1947 Portal to Portal Act essentially as a pro-employer law. And the liberal justices were supremely uninterested in the moral logic of employee compensation.
The opinion for the court, by Justice Clarence Thomas, in Integrity Staffing Solutions Inc. v. Busk, set the tone by its characterization of the environment in which the Portal to Portal Act first passed. The Supreme Court in the 1940s had held that employees must be paid for all time they were necessarily required by their employers to be on the premises. According to Thomas, these holdings produced a "flood of litigation," and "Congress responded swiftly" to meet the "emergency."
This is a contentious way to describe a lobbying process in which employers and unions fought it out and Congress adopted a law that balanced their interests. The law as passed said that employees wouldn't be paid for travel time to and from the job site. Then it added that they wouldn't be paid for "activities which are preliminary to or postliminary to said principal activity or activities."
The words "preliminary" and "postliminary" are hardly self- explanatory. The Supreme Court has historically interpreted those words to mean that employers must pay only for the work that is an "integral and indispensable part of the principal activities." So far, so good. The U.S. Court of Appeals for the Ninth Circuit, which considered the case, concluded that the process of forcing employees to undergo security screening after work counted as integral and indispensable — because it was, after all, considered indispensable by the employer.
The Supreme Court disagreed. Thomas' opinion observed that the court has found that putting on protective gear in a chemical plant and sharpening knives in a meatpacking facility count as integral and indispensable. It went on to say that screening after work is not the same because the screening isn't the principal work that employees are hired to perform. And the court reprimanded the Ninth Circuit for focusing on whether the screening was required by the employer, not whether it was a principal activity.
The Obama administration was on board with Amazon's contractor, which may help explain why the liberals went along. If you believe, as Thomas implied, that the Portal to Portal Act was simply a win for employers, then you might conclude that the law should be construed narrowly to avoid compensation. And it's also true that in principle, unions could in the future bargain specifically to get such compensation.
But there's still something fundamentally wrong with the court's formalistic reasoning. The trouble lies in the logic of defining "principal activity" as though it were some abstract philosophical question about the essence of the warehouse employees' job. In reality, the "principal activity" is the job as defined by the employer. Amazon need not define the job to require security screening, because of course you can work at a warehouse without stealing anything. But once the employer says that the job can only be performed if you get screened, it's redefining the principal activity from "warehouse work" to "warehouse work including screening."
Compare the court's examples of security gear. You don't work at the chemical plant in order to wear protective gear — it's just necessary if you want to do the job safely. Similarly, you don't need to be screened to fulfill orders in the warehouse — it's just that it's necessary (according to Amazon) if the job is to be performed profitably.
Ditto for knife sharpening. You can cut meat with a dull knife — but it reduces employer's profits if you do. An activity included in the job as part of the employer's profit motive should count as a principal activity.
The court's liberals should see this. They should have looked at the idea of "principal activity" in functional, economic terms — not like a problem in pure definition, but like a problem in the real world.
That none of them did is a sign of the slow and worrying creep of legal formalism into contemporary jurisprudence. Not to mention the slow death of unions. Amazon's warehouse workers, it turns out, never had a chance.
Noah Feldman, a Bloomberg View columnist, is a professor of constitutional and international law at Harvard.