This Wednesday, January 17, the Supreme Court will hear a case that demonstrates the practical power of the judiciary’s longstanding deference to administrative agencies. Encino Motorcars, LLC v. Navarro comes to the Court as a dispute over whether “service advisors” at car dealerships are exempt from the Fair Labor Standards Act’s overtime requirements. But its implications are far more sweeping.

Almost forty years ago, after a string of unsuccessful efforts in the federal courts to mandate overtime for service advisors, the Department of Labor issued an interpretation of “salesman” under the act that would exclude “service advisors” from the act’s overtime requirements. The retail automobile dealership industry relied on this interpretation over the following decades—basing compensation plans and myriad employment contracts on the understanding that federal law did not require “service advisors” to receive overtime pay.