A federal judge has ruled that the Justice Department unlawfully shared millions of voters’ records with Homeland Security Investigations, rebuking the Trump administration’s effort to collect voter information less than a month before the midterm elections. U.S. District Judge Sparkle Sooknanan found that the transfers to HSI, a division of Immigration and Customs Enforcement, violated the federal Privacy Act. The department sought information about registered voters without specific grounds to suspect they had committed election fraud or that their states had violated federal election laws, she wrote. “Behind all the window dressing, the challenged policy represents the federal government’s attempt to decide who gets to vote,” Sooknanan wrote, adding that the Constitution leaves that authority with the states. The decision followed more than a year of legal disputes over the administration’s efforts to obtain voter records. The Justice Department has lost at least 23 federal district court cases seeking to compel states to provide the information. The Supreme Court has also blocked a separate Trump administration plan to use the U.S. Postal Service to restrict voting by mail. At least 16 states voluntarily provided their voter rolls to the Justice Department, according to the Brennan Center for Justice. They are Alabama, Alaska, Arkansas, Florida, Indiana, Iowa, Louisiana, Mississippi, Nebraska, Ohio, Oklahoma, South Carolina, South Dakota, Tennessee, Texas and Wyoming. Internal reports released last week by the watchdog group Democracy Forward showed that HSI received nearly 51 million records from the Justice Department for what the agency called “election integrity” investigations. Those reports did not specify what the records contained. Sooknanan’s decision said the department had shared records on millions of voters with ICE. The judge cited a March 6 letter in which acting ICE Director Todd Lyons requested state voter lists so HSI could investigate potential violations of federal election law. A Justice Department attorney confirmed the data sharing in a March 12 response, writing that the agencies would take steps to limit effects on citizens’ privacy and civil liberties. Sooknanan warned that the department could not use a broad investigation of registered voters to sidestep Privacy Act protections, including those tied to free speech. The case was brought in April by voting-rights organization Common Cause and a group of voters. Common Cause President and CEO Virginia Kase Solomón called the ruling a victory for voters and urged the administration to stop seeking their private data. The Justice Department said it was reviewing the decision. The ruling is not expected to directly alter voting in the coming midterms. Justin Levitt, a Loyola Marymount University law professor and former White House voting-rights adviser, said most states never provided their voter files, and few states that did appear ready to act on information returned by the Justice Department. Separately, the Supreme Court in September allowed states to use the Department of Homeland Security’s SAVE system to check the citizenship status of individuals. But federal law generally limits mass voter-roll purges close to an election, and the system has had little effect on the upcoming midterms. Critics have pointed to cases in which SAVE incorrectly flagged U.S. citizens as possible noncitizens. A separate administration plan to create citizenship lists for each state also is unlikely to take effect before Election Day. President Donald Trump’s March executive order directs Homeland Security to work with the Social Security Administration to compile the lists and provide them to state officials. A Maryland federal judge has required the Justice Department to give at least 30 days’ notice before moving ahead, leaving too little time for the lists to be available before the midterms. The Maryland case, brought by the Electronic Privacy Information Center, could affect whether the lists are used in future elections. The group argues that the planned lists differ from SAVE because they would cover all U.S. citizens by state, rather than provide information only on individuals whose status is requested. The Justice Department disputes that distinction. The judge has not yet ruled.