A federal judge has barred the U.S. Department of Health and Human Services, led by Secretary Robert F. Kennedy Jr., from giving immigration authorities access to the personal information of Medicaid enrollees. In an order issued Tuesday, U.S. District Judge Vince Chhabria in San Francisco granted a preliminary injunction that blocks HHS and the Centers for Medicare and Medicaid Services from continuing data transfers to the Department of Homeland Security and Immigration and Customs Enforcement. The ruling stems from a lawsuit filed by 20 states after an Associated Press report revealed that CMS had quietly signed agreements in June and July giving DHS daily access to the names, Social Security numbers and addresses of all 79 million people enrolled in Medicaid. Chhabria wrote that using the data for immigration enforcement "threatens to significantly disrupt the operation of Medicaid" and said the policy lacked the “reasoned decision-making” required under administrative law. The injunction will remain in place until HHS can justify the program to the court. The health agency has argued the data-sharing accords are lawful but declined to say whether it will suspend them nationwide. State attorneys general, led by Washington, contend the disclosures deter vulnerable patients from seeking emergency medical care. The case could reshape how federal health data are used in immigration enforcement while testing the bounds of privacy protections under Medicaid.