The Riverside County sheriff and one-time gubernatorial candidate who seized more than half a million ballots in a 2025 special election must return them to county election officials, the California Supreme Court ruled Thursday.

Sheriff Chad Bianco in February seized approximately 650,000 ballots from a November 2025 special election on statewide congressional redistricting. The measure endorsed by Gov. Gavin Newsom passed in Riverside County by roughly 80,000 votes and easily passed statewide.

Bianco must also “refrain from further handling of the ballots except as necessary to comply with our order,” the court said in the unanimous decision.

Bianco said he confiscated the election materials as part of a criminal investigation he launched after receiving a complaint from a local citizens group that the count was off. Local election officials had previously said the complaint was unfounded.

Bianco, a Republican, was running for governor at the time, but he did not make it through the primary.

Democratic Attorney General Rob Bonta immediately launched a legal challenge, arguing the sheriff had no authority over election materials and warning the seizure was designed to sow distrust in elections. He ordered Bianco to return the ballots, but Bianco did not.

Bianco is running for California governor. Christian Cázares reports for the NBC4 News at 4 p.m. on Monday, March 23, 2026.

The University of California, Los Angeles Voting Rights Project also sued the sheriff and the Riverside County Registrar of Voters on behalf of several Riverside County voters.

The state Supreme Court last month heard arguments in both cases.

Bianco’s ballot investigation came as President Donald Trump has repeatedly disputed the results of the 2020 election, citing unsubstantiated instances of fraud. His administration in January seized ballots and other documents from an election office in Georgia.

Some Republicans have mirrored Trump’s rhetoric on voting in their states. Election officials and civil rights groups have been following the Bianco case carefully as they brace for the possibility that Trump or his allies may try to seize ballots in November.

NBC4’s Political Reporter Conan Nolan speaks with Riverside County Sheriff Chad Bianco, one of the two Republicans running for governor in California. He shares why he believes a Republican will win in the bluest state in the nation and why he blames the media for the controversy over his seizure of some 650,000 that were cast in Riverside County in last year’s special election.

California Gov. Gavin Newsom on Saturday signed a bill that would prevent anyone from seizing ballots, as Bianco did.

Bianco began recounting the vote shortly after seizing the ballots using sheriff’s officials under the supervision of a special master appointed by a court but suspended it days later, citing mounting legal challenges from the state attorney general and the voting rights group.

But he had not returned the ballots.

In a message to supporters, Bianco said he will comply with the order.

"I will obey the writs. I will not obey the message behind them — that local law enforcement works for Sacramento, not for the people who elected us," Bianco said. "My message to Bonta is simple: you may have succeeded in burying the truth—for now. But nothing stays hidden forever. In time, everything comes to light."

Bradley Hertz, who represented Bianco before the court, argued the sheriff had a legal duty to open a criminal investigation after receiving a complaint and he followed the penal code to carry out that investigation, first issuing search warrants in February. Hertz said Bianco has not returned the ballots to the Riverside County Registrar of Voters because those ballots are “evidence.”

At the time of the ballots’ seizure, Bianco was one of two prominent Republicans running for governor in a crowded June primary. He did not advance to the general election and later announced plans to run for reelection as sheriff in 2028.

Xavier Becerra, a former state attorney general and Democrat running for governor, is part of the UCLA lawsuit to halt Bianco’s efforts.

NBCLA's Jonathan Lloyd contributed to this report.