The American Civil Liberties Union of Minnesota sued Hennepin County on Monday on behalf of OccupyMPLS, the protest group camping out on the Government Center Plaza in downtown Minneapolis in defiance of county rules.

The ACLU suit contends that those rules, which forbid tents and electricity, and "certain unwritten procedures enforced by the county" violate the demonstrators' free speech rights.

Members of OccupyMPLS have been staying on the Hennepin County Government Center plaza night and day since Oct. 7 "to express their frustration with the growing economic and political inequities in this country," according to a news release from the ACLU-MN.

Carolyn Marinan, director of Hennepin County's public affairs department, said the county was expecting the suit.

"We're responding, and it would not be prudent or appropriate to say anything ahead of any legal proceedings," she said.

The suit asks that new rules restricting the use of chalk, electricity and tents be declared unconstitutional. The plaintiffs are also seeking an injunction against the rules, and they want the county to provide electricity for the protesters. It also asks that officials stop giving trespass notices to protesters who build temporary shelters or use chalk to express their views.

The county has said the plaza is not designed for long-term occupation and that the restrictions adopted earlier this month are needed because of health and safety concerns and increased security costs.

"The rules put forth by Hennepin County are particularly troubling because they were created as a direct response to OccupyMPLS," said Justin Perl, a partner at Maslon Edelman Borman & Brand, representing the protesters. "They are not based on any previous ordinances. The Constitution does not allow the government to just make up new rules as you go along in order to target a particular group."

The lawsuit names as defendants Hennepin County commissioners, Sheriff Rich Stanek and "unnamed sheriff's deputies and security officers."