Concerns about an influx of immigrants in Faribault, Minn., prompted the city to pass a rental housing law aimed at driving Somalis and other black residents out of town, the American Civil Liberties Union argued in a lawsuit filed Wednesday.

Six Faribault residents, along with Somali Community Resettlement Services, allege in a complaint filed in U.S. District Court that the city’s rental licensing ordinance is unconstitutional and “aimed at reducing the number of people of color living in rental housing within its borders.”

The suit was filed by lawyers for the national ACLU and its Minnesota branch.

In a letter to ACLU officials, a lawyer representing the city vigorously denied the allegations, calling them “unsubstantiated, inaccurate and contrary to law,” adding that demands to repeal the rental housing law were a “strong arm tactic.”

Faribault City Administrator Tim Murray said Wednesday that the city hadn’t had a chance to review the complaint and will consult with its lawyers before replying.

The rental licensing law, passed in 2014 and revised last year, requires landlords to get a rental license from the city. To get and keep the license, landlords must take part in the city’s Crime Free Housing Program.

According to the lawsuit, that program allows the city to evict renters if any member of the household or a guest engages in what police deem to be criminal activity, even if no arrest is made or charge filed. That means renters could be evicted, for example, if neighbors call police with complaints of excessive noise.

“It puts tremendous power in the hands of neighbors,” said Teresa Nelson, legal director of the ACLU in Minnesota.

One of the named black plaintiffs in the suit, Thelma Jones, was harassed by white neighbors “who would call the police about really petty things,” Nelson said.

Jones was forced to move in 2016 after repeated calls to the police by white neighbors about such things as family barbecues and children playing on a trampoline in the yard, according to court documents. She was never convicted of a crime, the lawsuit said.

“The City of Faribault labeled Ms. Jones and her family as problem tenants not as a result of confirmed criminal activity on her property, but as a result of harassing calls to the police from her white neighbors,” according to the lawsuit.

The rental housing law and the Crime Free Housing Program coincide with demographic changes Faribault has seen in recent years, the suit alleges. In 2000, the city’s population was 2.7 percent black, according to U.S. Census figures. By 2016, nearly 10 percent of Faribault residents were black.

The suit alleges that city officials became concerned after receiving complaints from residents about groups of Somalis congregating on downtown streets and sidewalks. According to the suit, one City Council member said in a local TV interview that Faribault needed to attract more high-income people “or we are going to flip like Detroit in a few years.”

Another part of the rental law limits the number of residents to twice the number of bedrooms, plus one, the suit said. That means no more than five people could rent a two-bedroom home or apartment.

The suit claims that clause unfairly targets Somali families, who tend to have larger families than average Minnesotans. Several Somali plaintiffs in the lawsuit were evicted from their rental homes when the birth of a new baby put them over the limit, according to court documents.

The city maintains that its housing law applies to all residents, no matter their race or nationality, according to the letter sent to the ACLU on behalf of the city from Robert Alsop, a Minneapolis attorney.

Alsop called claims of discrimination “deficient and unfounded.”