Both cases were brought by women who called themselves part of the “Free the Nipple” movement, which pushes for the ability of women to go topless in public as a way to promote equality.

The movement had a victory last September, when officials in Fort Collins, Colo., removed their ban on women and girls over 10 going topless in public following a ruling by the United States Court of Appeals for the 10th Circuit that said the ban was based on stereotypes that depicted women’s breasts as “sex objects.”

Ms. Buchanan’s case is different from those because she was topless in her own home, according to her lawyers.

The police in West Valley City, a suburb of Salt Lake City, learned of the episode in November 2018, about a year later.

Detectives were investigating unrelated allegations of sexual abuse when the biological mother of the children, who were about 13, 10 and 9 at the time, told them about the disrobing, according to court documents.

Randall W. Richards, one of Ms. Buchanan’s lawyers, said that the allegations had nothing to do with Ms. Buchanan, a 27-year-old test automation engineer. He declined to provide more details.

Ms. Buchanan was charged in early 2019. Mr. Richards said he believed the defense had a straightforward case.