The Trump administration has won a legal battle at the US Supreme Court over its use of a federal database to help states verify the citizenship status of registered voters.
The court's decision allows the Department of Homeland Security to continue sharing information through the Systematic Alien Verification for Entitlements (SAVE) programme, which states can use to check individual voters.
The administration expanded the programme last year to enable bulk searches using sensitive federal records, including Social Security data.
Supporters say the system is necessary to identify non-citizens who may be unlawfully registered to vote. Voting rights organisations, however, have questioned the accuracy of the data and warned that eligible citizens could be wrongly targeted.
The Supreme Court ruled that federal law permits the Department of Homeland Security to obtain citizenship and immigration information from other federal agencies and respond to requests from states.
At the same time, the ruling leaves in place restrictions on mass voter-roll removals shortly before an election.
The National Voter Registration Act bars broad purges during the period immediately preceding elections, meaning the decision has limited immediate implications for the upcoming midterms.
The court's three liberal justices disagreed with the decision.
Justice Ketanji Brown Jackson warned that erroneous checks could result in eligible Americans losing their right to vote, arguing that the consequences of disenfranchising lawful voters would outweigh any benefit to the government.
The dispute followed a June ruling by US District Judge Sparkle L. Sooknanan, who found that the government's expanded use of SAVE violated Americans' privacy rights and threatened voting rights.
A federal appeals court left that ruling intact before the Supreme Court overturned it on Friday.
SAVE was originally created in 1986 to allow government officials to verify immigration and citizenship information for people seeking public benefits.
Its use was later expanded by the Trump administration to assist states with voter citizenship checks.
Twenty-seven states currently use the database.
The League of Women Voters, which brought the case, criticised the Supreme Court decision, saying the system could expose millions of Americans to erroneous voter challenges.
The administration has defended the programme as a lawful measure to prevent non-citizens from voting.
But questions over its accuracy remain.
In Texas, officials in Travis County reportedly discovered that at least 10 per cent of nearly 100 people flagged by the system as non-citizens were actually US citizens.
Georgia has taken additional steps to verify information supplied through SAVE.
Secretary of State Brad Raffensperger said officials review the data and, in some cases, interview voters before determining whether they are eligible.
The Supreme Court ruling is the latest development in the Trump administration's efforts to reshape election administration, following other attempts to tighten voter verification and alter voting procedures.
