CONCORD, N.H. — The American Civil Liberties Union filed a lawsuit in federal court Wednesday that challenges the process of validating signatures on absentee ballots in New Hampshire.

The suit says current law allows election officials to reject an absentee ballot without giving notice to the voter, if they think there’s a signature mismatch in the voter’s paperwork. It also says it puts moderators in the difficult position of acting as handwriting experts.

The ACLU filed the suit against the secretary of state’s office on behalf of three absentee voters whose signatures were rejected. All voted in the 2016 general election, but didn’t learn their vote wasn’t counted until this year. One of them, Mary Saucedo, 94, of Manchester, is legally blind and is allowed to obtain assistance in completing the absentee ballot process. Her husband helps her.

“Voting means we have a say as to who should be in charge,” she said Wednesday in a statement. “In my household growing up during the Depression, it was very important to vote.” She said it was shocking and disturbing to learn her ballot was tossed out without notice.

Secretary of State William Gardner said he hasn’t seen the lawsuit, but said absentee voters are provided with instructions on marking and tracking their ballot. “On that instruction to voters in darker print it says, ‘Track your ballot’ and how to do it, where to go,” he said. The instructions provide the website, https://app.sos.nh.gov .

The lawsuit said the website isn’t updated until after the election, and by the time that information is available, it’s too late.

The suit asks that a section of law comparing signatures on voting affidavits to absentee ballot applications be declared unconstitutional, in violation of the U.S. Constitution and the Americans with Disabilities Act. It said people with disabilities are far more likely to have fluctuating handwriting or to require the assistance of someone to sign their name.

The ACLU says over the past five years, more than 500 voters in New Hampshire have been disenfranchised under the law.