According to the Fourth:
The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.This was written in response to the use of writs of assistance which allowed the bearer, typically the King's agents, to search any person and any home without further warrant in contravention of a long history of English law protecting a man's home as his castle. Even though any particular colonist had nothing to hide, the trespass of government agents into their homes and effects were unsettling to say the least.
Our own King George has fashioned his own writs of assistance in his domestic wiretapping fiasco. Case law is settled that wiretapping is covered by the Fourth Ammendment and US law makes provisions for obtaining a warrant after the fact where speed is of the essence in gathering information (a provision I believe could likely be found unconstitutional under careful review). The upshot being that intelligence agencies have no need of the powers usurped by BushCo.
Those who are unmoved by this breach of constitutional powers have not read their history. Bush and his legal team obviously have read their history; just the wrong parts. Our press? Don't even ask.