A Kansas law requiring proof of citzenship to register to vote has been ruled unconstitutional.

The law, championed by former Kansas Secretary of State Kris Kobach, took effect in 2013 but was blocked by a federal trial judge. A panel of the 10th Circuit Court of Appeals upheld this injunction, noting that while 31,000 applicants were prevented from registering under the law, only 39 nonresidents managed to register.

The law required anyone who attempted to register to vote in the state to provide documentation of US citizenship, such as a birth certificate or passport. The state can appeal this most recent decision to the full Court of Appeals, or could appeal it to the Supreme Court.