Common Access Cards as Voter ID: Considerations for Legislators

By Morgan Thomas, Policy Analyst

Verifying a voter’s identity is crucial to ensuring the integrity of the voting process and preventing fraud. The common access card (CAC) is a vital form of identification for U.S. Department of Defense personnel. It also serves as an acceptable form of photo identification when voting in person in several states. Because of this, some state legislators proposed legislation requiring absentee voters to submit a photocopy of their valid photo identification when returning their completed ballots. While a CAC can be photocopied under certain circumstances, federal law does not authorize an individual or election official to photocopy a CAC for absentee voting purposes. When drafting legislation, policymakers can consider the limitations of CAC usage under federal law while also exploring innovative ways to leverage them in elections.

What are CACs?

Those who have served in the U.S. Uniformed Services are likely familiar with the common access card. In today’s digital world, security and identification are more critical than ever, especially for military and government personnel. The CAC is an important tool for accessing sensitive information and enhancing voting security.

A CAC is issued to uniformed service personnel, DOD civilian employees, contractors and reservists. The CAC issuance process requires two forms of valid identification, sponsorship from a Department of Defense entity and previous registration on a Department database. CACs can be used for several functions, such as denoting military or civilian DOD employee status, accessing the DOD network, accessing military installations and more.

A CAC uses biometrics and a personal identification number to activate the data stored on the card’s chip and authenticate a DOD employee’s identity. The card contains physical information as well, including the card’s expiration date, a photograph of the cardholder, department affiliation, pay grade, rank, full name and other department-specific indications. The card does not indicate an individual’s citizenship status.

A CAC can only be used by DOD employees and the CAC holder is solely responsible for safeguarding their card. Using a CAC to obtain unauthorized benefits or privileges through counterfeiting, altering, or lending may result in a fine, imprisonment, or both. Instructions for how to manage a CAC can be found under 18 U.S.C. § 701 (1939), which addresses official badges, identification cards and other insignia.

While a CAC is used by personnel and contractors of the DOD, other departments of the federal government use a personal identity verification card (PIV). This card is a government-credentialed card or badge that federal employees and contractors use to access government facilities and systems. A PIV uses digital certificates and credentials to allow federal employees and contractors to access government facilities and networks.

Authorized Photocopying of a CAC

In addition to allowing access to DOD facilities and networks, a DOD CAC can be photocopied under specific authorized circumstances such as verifying medical coverage, administering military-related benefits to eligible beneficiaries and tax matters. For example, Tricare is the official health care program for members of the uniformed services and their eligible dependents. Medical providers are authorized to photocopy a CAC to verify health care coverage for service members and their eligible dependents.

Photocopying a CAC for unauthorized reasons is not allowed and is considered a federal crime under 18 U.S.C. § 701 (1939). Commercial establishments may ask to see someone’s CAC to verify their active-duty status for government-related benefits or services. However, commercial, nongovernment establishments are not authorized to photocopy a CAC. For example, an airport may ask to verify a CAC to grant a service member access to TSA Pre-Check or other airline specific military benefits. They are not authorized to photocopy the service member’s CAC.

CACs and Voting

As of February 2024, 36 states require voters to show a valid form of identification when voting in person. Service members who have recently experienced a permanent change of station (PCS) and moved, either domestically or abroad, face unique voting challenges. They may not possess an unexpired state-issued driver’s license, state identification card, U.S. passport or other valid form of photo identification for voting. Thus, a DOD CAC may be the primary form of identification for many active-duty service members.

In several states, members of the uniformed services are authorized to present their CAC as a form of photo identification when registering to vote or when casting their ballot in person on election day. Voters who are eligible to vote by mail, such as military servicemembers, their families and overseas voters, may be required to provide some form of identification alongside their absentee ballot. Some examples of authorized identification include the last four digits of a voter’s social security number, their state driver’s license number, a state-issued identification number or a U.S. passport identification number.

Recently, several states have proposed legislation requiring eligible absentee voters to submit a copy of an authorized form of photo identification, including military identification cards, when casting an absentee ballot. While CACs may be authorized for in-person voting purposes under 18 U.S.C. § 701 (1939), this does not extend to remote voting. When proposing photo identification laws, legislators should be mindful of federal limitations regarding photocopying a DOD CAC when voting remotely. In asking service members and DOD employees to photocopy their CAC, states could inadvertently require voters to commit a felony under U.S. Code. It should also be noted that the Help America Vote Act, section 303(b)(3)(c)(i) exempts UOCAVA absentee voters from identification requirements.

However, states can utilize the CAC to verify a voter’s identity in alternative ways. For example, states can allow federal personnel to digitally sign their ballot using a CAC or PIV rather than requiring a copy of a CAC. A digital signature uses a cryptographic mechanism to ensure confidentiality and verify the authenticity of digital documents through digital certificates. These digital certificates contain encrypted data to help confirm the user’s identity, making them difficult to forge.

Several states enacted legislation allowing some or all eligible voters covered under the Uniformed and Overseas Citizens Absentee Voters Act (UOCAVA) to utilize CAC or PIV digital signatures when voting. For example:

• Montana passed SB 0124 in 2019, allowing UOCAVA voters to use a digital signature on the federal postcard application when registering to vote, requesting an absentee ballot and marking their ballot.
• Michigan enacted SB 117 in 2019, allowing active–duty service members who are absent from the residence where they are registered to vote on election day to return an electronic ballot using a U.S. military-issued electronic email address. The bill also required these voters to digitally sign their electronic ballot using a CAC.
• Maryland Election Law Code § 3-202.1 (2024) allows active–duty military personnel, eligible reserve personnel, Department of Defense civilian employees, and eligible DOD contractor personnel to use a CAC to sign the Federal Post Card Application to apply to register to vote and apply for an absentee ballot.

While every state is different, leaders can consider the needs of UOCAVA voters when drafting voter identification laws. The Council of State Governments Overseas Voting Initiative report, “Using Technology to Enhance Military and Overseas Voting,” provides several recommendations to guide states’ use of CACs and digital signatures in elections. Additionally, the Federal Voting Assistance Program released a 2012 report on the feasibility of applying the Defense Information System Networks (DISN) in conjunction with CACs to serve as a reliable means of identification for DOD voters.

Eligible UOCAVA voters who are unsure of their state’s voter identification requirements should contact their local election official or check their Secretary of State’s website prior to completing any election materials. Voters can also reference the Federal Voting Assistance Program’s biennial Voting Assistance Guide and state-specific tools for completing online voting forms to learn about UOCAVA voting requirements in their state or territory.