There are some things that simply cannot be trademarked.
His opinion in 2012, and recently compounded with a lawsuit to deny the Myers brothers their trademark is clear. The M22 signs you see on apparel, coffee mugs, stickers on cars and used to profit a Northern Michigan business cannot be claimed for their exclusive use:
“.. In documents filed with the U.S. District Court in Grand Rapids, the state argues that highway signs can’t be registered and that trademarking signs violates the Manual on Uniform Traffic Control Devices (MUTCD), which sets the federal standards for signs, signals and pavement markings. Michigan Attorney General Bill Schuette wrote in a 2012 opinion that “no entity can lawfully claim exclusive control over use of the state’s highway route marker design, because the design is in the public domain and is otherwise not subject to protection under trademark law.” ..”
In other words, we all bought and paid for this design.