A federal judge ruled on Wednesday that a federal government database that compiles people deemed to be “known or suspected terrorists” violates the rights of American citizens who are on the watchlist, calling into question the constitutionality of a major tool the F.B.I. and the Department of Homeland Security use for screening potential terrorism suspects.

 

Being on the watchlist can restrict people from traveling or entering the country, subject them to greater scrutiny at airports and by the police, and deny them government benefits and contracts. In a 32-page opinion, Judge Anthony J. Trenga of United States District Court for the Eastern District of Virginia said the standard for inclusion in the database was too vague.