(CBS) — A woman ticketed in Chicago this summer for indecent exposure has now filed a federal civil rights lawsuit against the city, reports WBBM’s Steve Miller.

Sonoko Tagami was cited for indecent exposure at a Go Topless Day event this summer. The event was sponsored by an organization called “Go Topless.”

“One of its principles is that there should be gender equality in bare-chestedness; that if men can be bare-chested in public, women can be bare-chested in public,” said Tagami’s attorney, Kenneth Flaxman

Tagami, 41, was fined $140 for being topless at North Avenue Beach in August; or at least, in the eyes of a female police officer, Tagami was not conforming to the city’s indecent exposure ordinance, according to Flaxman.

The lawsuit claims the city’s ordinance is too vague, and discriminates against women. The city’s municipal code prohibits women from exposing “any portion of the breast at or below the upper edge of the areola,” by not concealing it with “an opaque covering.”

Tagami alleged the indecent exposure ordinance discriminates against women, as the city allows men to go topless in public.

Flaxman said Chicago has one of the strictest breast-centered ordinances in the country.

“It’s a poorly written, very very old ordinance that would, I think, make illegal many of the fashions that women wear today,” he said. “She believed she had appropriate body paint covering the naughty parts of her breasts,” he said.

The lawsuit notes Illinois state law allows women to bare their breasts while breastfeeding, and does not prohibit women from going topless, unless it is “done with intent to arouse or to satisfy [her] sexual desire.”

Flaxman said Tagami has appeared before – in a similar state of undress – on Go Topless Day in Chicago, and was never ticketed before, as male police officers stood nearby. This year, a female police officer took issue.

“A female police officer said, what you’re doing is illegal and I’m going to write you a ticket and if you don’t cover up I’m going to arrest you,” he said.

Flaxman said Tagami was ticketed and ordered to pay $140. Now she’s fighting it federal court.