The American Civil Liberties Union is suing the Kansas secretary of state, Kris Kobach, over a temporary regulation tossing votes from individuals who registered at a state motor vehicle office.

The ACLU claims the regulation violates both Kansas law and the state constitution. The rule allows those who did not show proof of citizenship to cast ballots in federal, but not state, elections.

Federal law allows people to register to vote at local motor vehicle offices. The rule was approved by the State Rules and Regulations Board after providing less than a day’s notice for the meeting. Members of the secretary of state’s office stated they believe they were following state law requiring new voters to show proof of citizenship.