A Utah woman who stripped to her waist while working in her own home is fighting multiple counts of lewdness that could lead to a jail term and placement on a sex offender registry.

Tilli Buchanan, who is 27, says she and her husband were doing renovation work in their garage when plaster dust prompted both to remove their upper garments, according to a letter from her lawyer, David Lane, to state prosecutors.

When her three stepchildren - aged nine, 10 and 13 - saw them, they expressed shock. Ms Buchanan told them that as a feminist she believed that she had as much right as her husband to go topless.

But word of the incident reached the children's birth mother - who considered the incident "alarming" - and eventually came to the attention of social services workers investigating a different matter, the Salt Lake Tribune reported.

That led to the filing of three charges of lewdness in front of children against Ms Buchanan, leaving her facing a possible year in prison and 10 years on the sex-offenders registry.

Being on that registry has debilitating effects, restricting areas where one can live, harming employment prospects and raising the possibility of losing custody of one's children.

Ms Buchanan's lawyer is demanding that the charges be dropped and her record expunged. In a letter to prosecutors he gave them until the end of next week to respond. 

"Because Tilli Buchanan is a woman," Mr Lane's letter states, "her bare chest is censured as being inherently pornographic and perverse, while her husband's bare chest is celebrated as an emblem of strength and pride."

"Tilli Buchanan is being singled out for prosecution solely on the basis of sex." 

The judge in the case has said a ruling will not come before early next year.

Utah is regularly ranked as one of the most conservative states in the US.