Washington (CNN) The Supreme Court on Thursday struck down a Minnesota law that banned political apparel at a polling place, holding that it violates the Free Speech Clause of the First Amendment.

The vote was 7-2.

The ruling could impact at least nine other states with similar laws and will send a message that states can't go too far in prohibiting speech at the polling place. Nearly every state has a law on the books that limits speech to some extent, but Minnesota's was considered one of the broadest for banning any "political badge, political button or other political insignia" at polling places.

Writing for the majority, Chief Justice John Roberts emphasized that states have "permissible objective" to make some prohibitions at the polling place but that Minnesota's law was vague at times and open to confusion.

"We see no basis for rejecting Minnesota's determination that some forms of advocacy should be excluded from the polling place, to set it aside as an island of calm in which voters can peacefully contemplate their choices," Roberts wrote.

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