In the original decision, the court made a startling declaration:
“police knowledge of the identity of an individual they have deemed ‘suspicious’ grants the police unfettered discretion to initiate or continue the investigation of the person long after the detention has ended. Information concerning the stop, the arrest and the individual’s identity may become part of a large scale data bank.”
In other words, by the mere act of showing the police your ID you are, in a very real sense, compromizing your freedom. Imagine volunteering to have the NSA catalog all your communications.