Voter Eligibility Challenges in California
November 3, 2026
By Thomas Callahan
On Oct. 15, 2026, the Department of Justice sued the State of California and Los Angeles County for not reviewing a list of 20,000 individuals it believed were unlawfully registered to vote in the State. On Oct. 28, a federal district court judge rejected the DOJ’s request that ballots cast by those individuals be segregated. While the DOJ has appealed the ruling, the Ninth Circuit also seems skeptical of the Department’s claims. Although DOJ’s efforts seemed to have hit a wall, California law has a process for challenging voter registration and voter eligibility both before and after voting starts.
Prior to an election, anyone can commence an action challenging the voter registration of an individual they believe is unlawfully registered to vote. The action must be brought in superior court, and the court has the power to make the challenged voter a party to the case. If successful, the court will compel the county election official to cancel the registration.
After voting starts, challenges are heard by a local precinct board. The precinct board is composed of individuals who reside in the precinct and are nominated by the central committee of each qualified political party. Members are appointed by county election officials prior to the election. While voting is ongoing, only members of the precinct board may challenge the eligibility of a voter at their polling place.
Board members may object to in-person voters on the grounds that:
(1) the voter is not the person they claim to be,
(2) the voter is not a resident of the precinct or county,
(3) the voter is not a citizen of the United States, or
(4) the voter has already voted in that election.
Board members may also object to votes cast by mail on the same four grounds, but they can also object on the grounds that:
(5) the ballot was not received within the correct time frame, or that
(6) the person who voted is currently serving time in either state or federal prison for a felony.
Members of the precinct board who initiate the challenge bear the burden of proof. For challenges to in-person voting, probable cause, which is to be determined by either the county election official or a deputy appointed by the election official, is needed to sustain a challenge. However, challenges to mail voting must be established by extraordinary proof, as the challenged voter is not present to defend themselves.
California law has a process by which board members can investigate challenges at the polling site. Board members have the authority to place challenged voters under oath and ask them questions about their eligibility. They also can place other individuals under oath and ask them about the eligibility of the challenged voter. For most challenges, a voter affirming that they meet the challenged criteria is enough to resolve the dispute in their favor. However, refusing to answer questions under oath is enough to prevent them from voting. Board members are required to document this process, including their determination of the voter’s eligibility and any evidence discovered.
California law also provides means of protecting the challenge system from abuse. Any doubt in interpreting a law is resolved in the favor of the challenged voter; voters who moved out of the district within 14 days of the election cannot be challenged on residency grounds; and mail returned as undeliverable cannot be used as a basis, or as evidence, to challenge residency. Additionally, board members have the ability to discontinue voter challenges if they feel that persistent challenges are dissuading people from voting, either out of a concern for voter intimidation or because of long delays in voting.
If a challenge is overruled, the ballot is counted normally, but if a challenge succeeds, the ballot is marked with the reason for granting the challenge and then segregated from other ballots. There is also a provision of California law which allows for ballots to be challenged for incompleteness, ambiguity or other defects during a recount.