A federal appeals court heard arguments Tuesday in the case of a woman who was ticketed after she took off her shirt at a GoTopless Day protest in Chicago in 2014.

Sonoko Tagami got the $100 ticket for indecent exposure, a ticket that she appealed. A city hearing officer ruled against her, but encouraged her to file a federal civil-rights lawsuit, according to court documents. So she did.

Her lawsuit claims the city violated her First Amendment right to protest and — since men get to go topless — her 14th Amendment right to equal protection.

In February, a federal circuit court judge dismissed the case without a trial. A three-judge panel for the U.S. Seventh Circuit is now considering her appeal.

Legal briefs filed in the run-up to this week’s hearing are full of unusual details. The city cites cases like “Foxxxy Ladyz Adult World, Inc. v. Village of Dix” and “Sensations, Inc. v. City of Grand Rapids.”

Tagami’s legal briefs include a link to “an image of plaintiff during the (protest), which may be considered ‘not safe for work.’ ”

Tagami’s suit also includes images of a “crochet pushup halterkini” sold at J.C. Penney as part of an argument the city’s public-nudity ordinance is out of step with contemporary norms.

Specifically, the city ordinance bars people from exposing “any portion of the breast at or below the upper edge of the areola thereof of any female person.”

Tuesday’s appellate hearing focused on technical legal questions, like: Is going topless, in this context, an expressive act?

An attorney for the city of Chicago argued it is not.

“The court found in the Foxxxy Ladyz case that nudity is not inherently expressive,” Jonathon Bryer told the three-judge panel.

At least one judge was unpersuaded. Given that protesters were holding up signs, explaining the point of their protest.

“Why was [Tagami’s] conduct not inherently expressive?” asked Judge Ilana Rovner.

“Speech doesn’t change the conduct,” Bryer said.

In fact, holding up a sign or otherwise explaining the conduct, Bryer claimed, “shows that the conduct was not expressive.”

Rovner also questioned whether Tagami’s challenge to the city’s law against public nudity could be dismissed without a trial.

“At one time, it was prohibited for men to expose their breasts,” Rovner said. “Attitudes changed, and prohibitions fell away.”

If nothing else, Rovner said, the question could be worth debating in court.

Another judge suggested an argument he would have found persuasive: the idea that the city only enforces its public-nudity law when protest is involved.

“I didn’t see that in your brief,” said Judge Frank Easterbrook. “I looked. When a woman wears a risque gown to a Lyric Opera ball, the ordinance is not enforced (but protest draws a penalty).”

Tagami’s attorney, Joel Flaxman, said he thought he had covered that, by noting how a blanket enforcement of the ordinance would lead to outlawing the J.C. Penney halterkini.

Easterbrook wasn’t having it.

“That would be a stupid law,” he said. “But there is a large category of stupid-but-constitutional laws.”

A previous version of this story misidentified the amendment which assures a right to equal protection. It is the 14th amendment. It also misspelled the name of the store that carries the halterkini noted in the suit. It is J.C. Penney.

Dan Weissmann is a WBEZ reporter. Follow him @danweissmann.