By Emma Gannon, Courthouse News Service

DENVER (CN) — A Free the Nipple chapter, a "non-binary person" and a city resident sued Fort Collins, Colo., for criminalizing women, but not men, who expose their nipples in public.

The Free the Nipple Movement, which began in 2014 with Lina Esco's film of the same name, uses grassroots campaigns and social media to fight discriminatory laws about breasts.

The Fort Collins chapter of the unincorporated association filed a federal complaint Tuesday, challenging Section 17-142 of the city's indecency code, which states: "No person shall knowingly appear in any public place in a nude state or state of undress such that the genitals or buttocks of either sex or the breast or breasts of a female are exposed."

Free the Nipple wastes no time in stating its position. The lawsuit begins: "Plaintiffs challenge a sexist ordinance that is based on antiquated social mores; justification for the ordinance is rooted in outdated nineteenth century puritanical values and discrimination, nothing more.

"Plaintiffs are a woman, a non-binary person, and an unincorporated association of men, women, and LGBTQIA persons who believe in equality. They have focused upon the double standards, hypocrisies, and sexualization of the feminine upper body that underlie government efforts to censor feminine breasts. They strive for gender equality."

Female toplessness has been legalized in parts of 30 states, including Colorado. Boulder, 45 miles from Fort Collins, has accepted female toplessness and become a favorite spot for nudists.

Free the Nipple says Fort Collins' ordinance is not only discriminatory, it also criminalizes revealing clothing. The group calls it "one of the most restrictive public nudity ordinances in the nation."

"If a woman were to wear a plunging neckline dress, thereby exposing either side of her breast; a microkini, thereby exposing the bottom portion of her breast; or pasties, thereby covering only her nipple and exposing the rest of her breast, that woman would be in violation of Section 17-142 and subject to criminal punishment."

Plaintiffs' attorney David Lane and the city of Fort Collins did not immediately respond to requests for comment.

The group seeks declaratory judgment that the law violates the First Amendment and the constitutional guarantee of equal protection, and an injunction against its enforcement.

To Learn More:

New Hampshire Bill Criminalizing Female Breast Exposure Shot Down by Lawmakers (Associated Press)

New Hampshire Lawmakers Move to Criminalize Public Female Breast Exposure, Warning of Rampant Topless Women at Libraries and Little League Games (by Kathleen Ronayne, Associated Press)

Springfield, Missouri Criminalizes Breastfeeding in Public because it might Offend Tourists (by Noel Brinkerhoff and Steve Straehley, AllGov)

New York City Police Officers Reminded to Allow Women to Bare their Breasts in Public (by Noel Brinkerhoff, AllGov)

The Battle over Nipple Exposure in North Carolina (by Matt Bewig, AllGov)