It short-circuits the fourth ammendment, which protects against unreasonable searches. The way this is enforced in the real world is that evidence is thrown out of court if it was obtained in an unlawful search. With parallel construction, you render useless the <i>only</i> enforcement mechanism for the fourth ammendment.<p>Not to mention the deception. In order to use parallel construction, the police need to make up a story about why they began investigating. By definition, parallel construction means that they will lie in court about this.<p>The courts really need to wake up, or they will continue to be impotent lackeys of the executive branch.