From the NRA-ILA:
The Supreme Court struck down a Minnesota law that forbade voters from wearing “political insignias” at polling places after the law was challenged by a voter who was told he must remove or cover his Tea Party shirt.
It is beyond a doubt that the state’s application of the law unfairly discriminated against the free speech of NRA members. The lawyer for the state himself told the court that, under the law, a shirt with the slogan “Parkland Strong” would be permissible, while an NRA shirt would not. Ironically, while a shirt displaying the text of the First Amendment would be allowed, a Second Amendment shirt, which “could be viewed as political” would not.
The Supreme Court was right to conclude that the vague standards set by the Minnesota law violated the right to free speech. Since a polling place is considered a public forum, government restrictions on speech may not discriminate based on speakers viewpoints. Clearly, Minnesota’s interpretation of what constituted forbidden “political insignias” was biased against the viewpoint of gun rights advocates.