The researchers say the cases are those they could confirm with direct evidence connecting a license-plate search to a known immigration arrest. They also found more than 1 million successful searches by immigration enforcement, though that figure does not establish how many searches led to arrests or involved civil immigration violations.

The report examines four ways federal immigration authorities can obtain driver information: state Department of Licensing records, law-enforcement information networks, private data brokers and cooperation from local or state agencies. Researchers compared Washington’s protections with policies in New York, Maryland and Minnesota, finding gaps in enforcement and consistency across the states.

Washington’s Keep Washington Working Act generally bars state agencies from sharing information for civil immigration enforcement. But federal agencies can seek records through other channels, including Nlets, a national law-enforcement network connected to Washington’s ACCESS system, which is managed by the State Patrol. The report says nearly 20,000 users at about 500 agencies can access the platform.

“When you cut off one pathway, you squeeze a balloon, and another bubbles out,” said Angelina Godoy, director of the UW Center for Human Rights.

The governor’s office said it has blocked nearly 2,000 information requests, largely from Customs and Border Protection, and disabled 16 agency identifiers that it determined were being used for civil immigration enforcement. Gov. Bob Ferguson said the state was working to limit federal access for immigration enforcement while preserving access needed for public safety.

Researchers welcomed those steps but said they are not enough. They reported that agents whose access is blocked may use another agent’s account, and argued that safeguards must address all four routes through which records can be obtained.

The report also raises concerns about data brokers that buy state driver records and resell access. Washington requires that the records not be used for civil immigration enforcement, but the researchers said contracts and anonymous searches can make it difficult to audit how buyers use the data. One contract cited in the report allows ICE to search LexisNexis anonymously.

Washington was the first of the four states examined to make driver’s licenses broadly available regardless of immigration status. Advocates say using licensing information to locate and arrest immigrants undermines the purpose of that policy and can discourage people from driving to work, seeking medical care or taking part in daily life.

Guillermo Rivera, a community organizer who helped researchers compile the report, said families have watched location information show a detained parent being taken to the Northwest ICE Processing Center in Tacoma. He called on the governor to act quickly to close gaps in state protections.

The governor’s office said it is reviewing whether and how the state could require judicial warrants for federal requests related to civil immigration enforcement. The UW researchers recommend warrants alongside other restrictions. They noted that Washington, unlike some of the other states studied, does not currently require a judicial warrant for federal immigration authorities to access state-held driver and vehicle data.