A small town in Missouri has told its residents they cannot post political protest signs—or any other type of political-issue signs—on their own property. According to the Clinton County Leader, the issue began when residents of the town of Plattsburg posted protest signs opposing the construction of wind turbines in the area. Other signs however, like election signs and real estate signs, are still allowed in front yards under its sign code.

“This is an absolute violation of the First Amendment,” said Erica Smith, Attorney at the Institute for Justice. “Political protest signs are core political speech. What’s more is that these sign restrictions discriminate based on content–completely contrary to clear Supreme Court precedent.”

Last summer, the United States Supreme Court struck down a sign code for being “content based,” meaning it restricted some signs but not others, based purely on the signs’ subject matter. The Supreme Court was clear that such content based restrictions are unconstitutional under the First Amendment.

According to the report, residents will receive a warning first, followed by a notice of violation, and then a citation.