Today the U.S. Supreme Court issued its opinion in American Trucking Associations, Inc. v. City of Los Angeles. That decision held that some provision of the Clean Truck Program was preempted by the Federal Aviation Administration Act of 1994. The Port of Los Angeles may no longer force drivers to display “How Am I Driving” signs. Nor can the Port require trucking companies to submit off street parking plans for trucks. You can read the opinion here.