prohibiting advertising on commercial vehicles--unless the advertisement concerns the vehicle owner's own business.

http://law2.umkc.edu/faculty/projects/ftrials/conlaw/epcscrutiny.htm Over recent decades, the Supreme Court has developed a three-tiered approach to analysis under the Equal Protection Clause.   Most classifications, as the Railway Express and Kotch cases illustrate, are subject only to rational basis review.  Railway Express upholds a New York City ordinance prohibiting advertising on commercial vehicles--unless the advertisement concerns the vehicle owner's own business.  The ordinance, aimed at reducing distractions to drivers, was underinclusive (it applied to some, but not all, distracting vehicles), but the Court said the classification was rationally related to a legitimate end.