PORTLAND — Three residents are suing the city to overturn a recently enacted ban on loitering in street medians.

The American Civil Liberties Union of Maine and Boston law firm Goodwin Procter brought the suit Tuesday on behalf of Michael W. Cutting, Wells Staley-Mays and Alison E. Prior.

The ban, which took effect Aug. 15, prohibits pedestrians from staying on medians except to cross the street. The ordinance was unanimously approved in July by the City Council, which described it as a public safety measure.

But critics have claimed it is a thinly disguised attempt to clamp down on panhandling.

The ACLU had long threatened legal action against the city if the ban was approved. In a press release Wednesday morning, the group said the ordinance was “overbroad” and violates the residents’ constitutional rights to free speech.

The ACLU described Cutting and Staley-Mays as activists who have stood in medians holding political signs. Prior is homeless, and has stood in medians asking for food and money, according to the release.

“While this ordinance was framed as an effort to protect public safety, in reality it prohibits a significant amount of peaceful, non-threatening, constitutionally protected speech,” Zachary Heiden, legal director of the ACLU of Maine, said.

“The city of Portland should not be in the business of telling people where they can and cannot exercise their constitutional rights,” Heiden said, “and it should certainly not be banning speech in an area that has traditionally been used as a forum for public dialogue.”

William Hall can be reached at 781-3661 ext. 106 or whall@theforecaster.net. Follow him on Twitter: @hallwilliam4.