President Donald Trump made no statement about the federal holiday that commemorates the end of slavery in the United States, other than saying there were too many like it. Lesser occasions routinely garner official proclamations.

In a unanimous, 38-page ruling, a three-judge panel of the U.S. Court of Appeals for the Ninth Circuit held that the conditions in Los Angeles were sufficient for Mr. Trump to decide that he needed to take federal control of California’s National Guard and deploy it to ensure that federal immigration laws would be enforced.