According to CNN, a federal appeals court ruled against an Arizona law requiring residents to prove their U.S. citizenship to register to vote, but upheld a part of the same law that mandates residents to show identification before voting. 

The decision made by the Ninth Circuit Court of Appeals in San Francisco last week was part of an ongoing court battle surrounding Arizona's Proposition 200. 

What does this mean for voters tommorow? 

It means you must bring ID in order to cast your ballot.  As noted on the AZ Secretary of State website, and required as part of voter approved proposition 200:

IMPORTANT NOTICE: ID at the polls is required for all Arizona elections.

Every qualified elector is required to show proof of identity at the polling place before receiving a ballot. The elector shall announce his/her name and place of residence or present the elector’s name and residence in writing to the election official. The elector shall present acceptable identification that:

1. Bears the name, address, and photograph of the elector (See List 1), or
2. Two different forms of identification that bear the name and address of the elector (See List 2), or
3. One form of acceptable photo identification with one form of non-photo identification that bears the name and address of the elector (See List 3)

List 1 - Acceptable forms of identification with photograph, name, and address of the elector

• Valid Arizona driver license
• Valid Arizona non-operating identification license
• Tribal enrollment card or other form of tribal identification
• Valid United States federal, state, or local government issued identification

An identification is "valid" unless it can be determined on its face that it has expired.

List 2 - Acceptable forms of identification without a photograph that bear the name and address of the elector (two required)

• Utility bill of the elector that is dated within 90 days of the date of the election. A utility bill may be for electric, gas, water, solid waste, sewer, telephone, cellular phone, or cable television
• Bank or credit union statement that is dated within 90 days of the date of the election
• Valid Arizona Vehicle Registration
• Indian census card
• Property tax statement of the elector's residence
• Tribal enrollment card or other form of tribal identification
• Arizona vehicle insurance card
• Recorder's Certificate
• Valid United States federal, state, or local government issued identification, including a voter registration card issued by the County Recorder
• Any mailing to the elector marked “Official Election Material”

An identification is "valid" unless it can be determined on its face that it has expired.

List 3 - Acceptable forms of identification, one identification with name and photo of the elector accompanied by one non-photo identification with name and address

• Any valid photo identification from List 1 in which the address does not reasonably match the precinct register accompanied by a non-photo identification from List 2 in which the address does reasonably match the precinct register
• U.S. Passport without address and one valid item from List 2
• U.S. Military identification without address and one valid item from List 2

An identification is "valid" unless it can be determined on its face that it has expired.