WASHINGTON (Reuters) - States cannot impose a blanket prohibition on apparel such as T-shirts and buttons bearing political messages in polling sites, the U.S. Supreme Court said on Thursday in an important free speech ruling striking down a Minnesota law as unconstitutional.

The U.S. Supreme Court is seen as the court nears the end of its term in Washington, U.S., June 11, 2018. REUTERS/Erin Schaff

The court ruled 7-2 that Minnesota’s law, which dates back to 1912 and was intended to maintain decorum at polling sites, went too far in banning voters from wearing political apparel - without even defining what is meant by “political.” But the justices left room for states to craft some sort of limits on what should be allowed in polling places and what should not.

Minnesota’s law barred people from wearing clothing, badges, buttons or other insignia with overtly political messages inside polling places during primary or general elections.

In a ruling issued against a backdrop of deepening political polarization in America, the Supreme Court endorsed the argument advanced by the conservative activists who challenged the law in 2010, finding that it violated the U.S. Constitution’s First Amendment guarantee of freedom of speech.

Writing for the court, Chief Justice John Roberts said because Minnesota’s law did not define the term “political” the measure could be haphazardly enforced at polling sites. He wondered in the ruling whether a “Support Our Troops” shirt could be banned, or one displaying “#MeToo,” referring to a movement encouraging women to share their experiences of abuse.

Minnesota had argued that the law was applied neutrally and helped prevent confusion or intimidation at polling places.

While Minnesota had tried to promote voting “in a setting removed from the clamor and din of electioneering,” Roberts wrote, the state “has not supported its good intentions with a law capable of reasoned application.”

Still, Roberts said, states can prohibit certain apparel at polling places to avoid the partisan discord that can be associated with an election.

Roberts was joined by the court’s four other conservatives as well as liberal Justices Ruth Bader Ginsburg and Elena Kagan. Liberals Sonia Sotomayor and Stephen Breyer dissented.

‘ARBITERS OF FREE SPEECH’

“The court put all government entities on notice - they cannot dictate the terms of personal expression, nor can they designate the arbiters of free speech at their whim,” said attorney David Breemer of the conservative Pacific Legal Foundation, which represented the law’s challengers.

By protecting speech in a sensitive place like a polling site, the group said, the ruling safeguards expression in other forums as well such as airports, town halls and college campuses.

Minnesota Secretary of State Steve Simon said he was gratified that the court recognized “the vital interest of maintaining an ‘island of calm’ in our polling places.”

“The (Minnesota) legislature now must change Minnesota law so that it is entirely consistent with the right of free speech and expression - while also maintaining the sanctity of the polling place,” Simon added.

Delaware, Kansas, Montana, New Jersey, New York, Tennessee, Texas, Vermont and South Carolina impose restrictions similar to Minnesota’s.

In another major ruling involving free speech at polling sites, the high court in 1992 upheld a Tennessee law barring the solicitation of votes and the display or distribution of campaign material within 100 feet (30 meters) of a polling place.

One of the conservative activists who challenged the law, Andy Cilek of the St. Paul-based Minnesota Voters Alliance, was stopped by a poll worker when he showed up on Election Day in 2010 wearing a T-shirt touting the conservative Tea Party movement with the words “Don’t Tread on Me” as well as a button stating, “Please I.D. Me.”

Cilek eventually was allowed to vote. Violators were asked to cover up or remove offending items, and officials were instructed not to bar anyone from voting. Minnesota had no record of any prosecutions under the law.

After the ruling, Cilek said that “we showed that our right to free speech doesn’t stop at the polling place.”