A Texas appeals court on Thursday upheld a five-year prison sentence for a woman who was convicted of illegally voting even though she didn't know she was ineligible when she went to the polls in 2016. The punishment for the Fort Worth woman, Crystal Mason, stirred national outrage because of its severity, prompting accusations that prosecutors were trying to intimidate Texans from voting. Four years ago, Mason was on supervised release, similar to probation, for a federal felony conviction. Mason voted in the last presidential election at the urging of her mother and cast a provisional ballot. The ballot was never counted because Mason was not an eligible voter. During her 2018 trial probation officials testified that they never told Mason she could not vote, but the appeals court said that didn't matter. Mason was guilty, the court said, because she knew she was on supervised release. Texas is one of 48 states that strip people with felony convictions of the right to vote, but the rules on when people regain the right to vote vary widely from state to state and are often extremely confusing, even to elections officials. The decision to prosecute Mason was unusual. Since 2014, at least 12,668 people have voted using a provisional ballot in Tarrant county and 88% of them have been rejected because the voter was not eligible. Mason is the only voter who used a provisional ballot who was prosecuted for illegal voting.