The last-minute decision from the judge came on the state's original registration deadline of Oct. 5.
Two nonprofit organizations, Mi Familia Vota and the Arizona Coalition for Change, and an individual voter organizer with Mi Familia Vota, Ulises Ventura, filed the complaint seeking an extension on the registration deadline.
On Oct. 7, the 9th Circuit Court of Appeals denied a motion by the Republican National Committee to stop the extension of Arizona's voter registration deadline.
"The Maricopa County Recorder's Office is processing voter registration and is working with our attorneys, the Arizona Secretary of State and other counties to implement procedures that would comply with the agreement while also ensuring the integrity of this election," read a statement from Maricopa County Recorder Adrian Fontes.
Eligible voters may register at http://servicearizona.com if one has an Arizona ID, or by downloading the paper form at http://register.maricopa.vote.