SEATTLE—A federal judge on Saturday partially lifted a Trump administration ban on certain refugees after two groups argued that the policy prevented people from some mostly Muslim countries from reuniting with family living legally in the U.S.

U.S. District Judge James Robart heard arguments Thursday in lawsuits from the American Civil Liberties Union and Jewish Family Service, which say the ban causes irreparable harm and puts some people at risk. Government lawyers said the ban is needed to protect national security.

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