“By weighing in at more than 6,000 pounds, big SUVs are prohibited on thousands of miles of road in California. Cities across the state—including San Francisco, Los Angeles, Pasadena, and Santa Monica—use the 3-ton cutoff for many or nearly all of their residential streets. However, prosecution of the Golden State’s ban on big SUVs is a contender for the least enforced traffic regulation in America.

Those who take the federal and state tax breaks for their heavy SUVs are happy to accept the GVWR as their vehicle’s official weight. After all, they must be over 6K to get the write-off. Yet now they’re arguing that the actual weight of the vehicle as it rides along California streets may—may—be slightly under 6K. Pick a number and stick with it.