Privacy protection in the past had little to do with ordinary criminal procedure. The Fourth and Fifth Amendments arose out of heresy investigations and seditious libel cases, not murders and robberies. Except for the last generation or so, that history has had surprisingly little to do with the police. It has had more to do with the substantive law of crimes, with what activities the government should and should not be able to punish. Of course, the substantive issues that shaped Fourth and Fifth Amendment law are long since settled. Meanwhile, the law of criminal procedure still follows the path marked out by these old battles. We have taken a privacy ideal formed in heresy cases and railroad regulation disputes, an ideal that had no connection to ordinary criminal law enforcement, and used it as the foundation for much of the vast body of law that polices the police. Predictably, the combination has not worked out very well.
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