A federal appeals court will decide whether Kansas has the right to ask people who register to vote when they get their driver's licenses for proof that they're citizens, a decision which could affect whether thousands have their ballots counted in November's election.

Three judges from the 10th Circuit Court of Appeals heard arguments in the case Tuesday from Kansas Secretary of State Kris Kobach and the American Civil Liberties Union but didn't indicate how soon they could rule.

Kansas wants the court to overturn a ruling by a federal judge in May that temporarily blocked the state from disenfranchising people who registered at motor vehicle offices but didn't provide documents such as birth certificates or naturalization papers. That was about 18,000 people at the time. If the order is allowed to stand, the state says up to an estimated 50,000 people who haven't proven they're citizens could have their votes counted in the fall.

Since 1993, states have had to allow people to register to vote when they apply for or renew their driver's licenses. The so-called motor-voter law says that people can only be asked for "minimal information" when registering to vote, allowing them to simply affirm they are citizens.

The ACLU claims the law intended to increase registration doesn't allow states to ask applicants for extra documents. It also says that motor vehicle clerks don't tell people renewing existing licenses that they need to provide the documents, leaving them under the mistaken impression that their registration is complete when they leave the office.