CHICAGO — Chicago on Wednesday filed a motion to dismiss a federal lawsuit over the right of women to go topless in Chicago, arguing that nudity is not protected expression under the Constitution and that “female breasts are considered erogenous in a way that male breasts are not.”

“The (Indecent Exposure or Dress) Ordinance is substantially related to the City’s important objectives in ensuring public safety and protecting unwilling audiences from exposure to nudity, which, consistent with current community standards, includes the exposure of female breasts,” city lawyers wrote in their response.

The lawsuit was filed in U.S. District Court in November on behalf of Sonoko Tagami, then 41, who was described as an ardent supporter of GoTopless, a nonprofit that “advocates for the right of women to appear bare-chested in public.”

Chicago police ticketed Tagami for indecent exposure last August during an event at Chicago’s lakefront to promote the right of women to bare their breasts in public. An administrative law judge found her liable and ordered her to pay a $100 fine plus additional costs.

Tagami’s suit claims the city’s ordinance barring women from exposing “any portion of the breast at or below the upper edge of the areola” is unconstitutionally vague and a violation of free speech. The suit also alleges that because men are excluded from that portion of the ordinance, it violates rights to equal protection under the law.

Her lawyer, Kenneth Flaxman, called the city’s stance “puritanical” and noted that women are allowed to breast-feed in public.

“She was making a statement that the ordinance should be repealed, that it is unfair to women and that women’s breasts are not dirty and shouldn’t have to be covered in public,” Flaxman said. “That if women want to be top-free, they should be allowed to be top-free.”