These Fourth Amendment freedoms cannot properly be guaranteed if domestic security surveillances may be conducted solely within the discretion of the Executive Branch. The Fourth Amendment does not contemplate the executive officers of Government as neutral and disinterested magistrates. Their duty and responsibility are to enforce the laws, to investigate, and to prosecute.... But those charged with this investigative and prosecutorial duty should not be the sole judges of when to utilize constitutionally sensitive means in pursuing their tasks. The historical judgment, which the Fourth Amendment accepts, is that unreviewed executive discretion may yield too readily to pressures to obtain incriminating evidence and overlook potential invasions of privacy and protected speech.
-- Justice Powell writing for a unanimous Supreme Court
United States v. United States District Court (1972) [via]
Impeach George Bush. Impeach him now. (As Brad DeLong would say.)