The government’s jailing of terrorism witnesses for a grand jury probe of the Sept. 11 terrorist attacks is unconstitutional, a federal judge concluded Tuesday in dismissing a perjury case against a Jordanian college student. In a ruling that, if upheld, would have far reaching implications on the government’s approach to investigating terrorism, Judge Shira Scheindlin attacked the reasoning of Attorney General John Ashcroft. She criticized Ashcroft’s reported statement that “aggressive detention of lawbreakers and material witnesses is vital to preventing, disrupting or delaying new attacks.” Scheindlin wrote that “Relying on the material witness statute to detain people who are presumed...