Crystal Mason, 44, from Fort Worth in Texas, said she did not realise she was not allowed to cast a ballot in the 2016 presidential election due to being on supervised release for a federal felony conviction related to tax fraud.

Ms Mason cast a provisional ballot which was ultimately not counted in the election, but was convicted in 2018 of voting while on supervised release and sentenced to five years in prison.

She appealed to the Court of Appeals for the Second District of Texas with support from the local chapter of the American Civil Liberties Union (ACLU) and others, but a three-judge panel rejected her appeal.

The civil rights organizations and criminal defence lawyers representing her will seek to have the full Court of Appeals review her appeal, the next step available in the process.

Ms Mason is represented by the ACLU of Texas, ACLU Voting Rights Project, Texas Civil Rights Project, and her criminal defence lawyers Alison Grinter and Kim Cole.

The arguments presented on appeal focused on Mason’s lack of knowledge that the state considered her ineligible to vote, and that the statutes under which she was punished were not clear enough to give any voter in her situation adequate notice that what she did was unlawful.

Tommy Buser-Clancy, senior staff attorney for the ACLU of Texas, said: “We are disappointed with the decision and believe that it is wrong on the law. Crystal submitted a provisional ballot that was not counted, she did not vote illegally.

“We will continue to fight on behalf of Crystal by asking the entire Second Court of Appeals to re-hear this decision.”

Ms Grinter added: “This ruling is a severe misinterpretation of the law. It undercuts efforts to encourage voter turnout through the Help America Vote Act and punishes ordinary voters for attempting to fulfill their civic duty in a way that is at complete odds with our democratic principles.”