The lawsuit said security guards last February prevented activists with Moratorium Now! from handing out flyers about the city’s bankruptcy and gathering petition signatures, threatening them with arrest.

During the incident, a Detroit police sergeant told the activists they would have to leave because the park’s private management company made the rules and didn’t want them demonstrating there, the suit said.

The activists’ treatment is a violation of free speech because Campus Martius is a public park owned by the city, said Michael Steinberg, legal director for the ACLU of Michigan. The park’s management firm cannot be allowed to treat Campus Martius like private property, he said.

“While the city may delegate the responsibility for managing the park to a private entity, they simply cannot sign away people’s rights,” Steinberg said. “Campus Martius is a public park owned by the city of Detroit, for the people of the city of Detroit. They should be able to express their views on matters of public importance there just like any other public park.”

Campus Martius, at…