Memorandum: Congressional Research Service on Warrantless Surveillance
The underlying issue is whether the Authorization for the Use of Military Force passed immediately after the attacks of September 11, 2001, gave President Bush the authority to direct the National Security Agency (NSA) to conduct selective warrantless nonconsensual interceptions of US citizens' communications.
The CRS memorandum states the crux of the matter in the paragraph which reads:
"The Administration's views have been the subject of this debate. Critics challenge the notions that federal statutes regarding government eavesdropping may be bypassed by executive order, or that such laws were implicitly superseded by Congress's authorization to use military force. Others, however, have expressed the view that established wiretape provisions are too cumbersome and slow to be effective in the war against terrorism, and that the threat of terrorism justifies extraordinary measures the President deems appropriate, and some agree that Congress authorized the measures when it authorized the use of military force."
The linked memorandum lays out a general framework for analyzing the constitutional and statutory issues raised by NSA's electronic surveillances. It also outlines the legal statutes regulating government electronic surveillance, examines the ambiguities in the statutes that could provide justification for the NSA's actions, and addresses the question of whether the President has the inherent authority he claims or whether Congress has already provided that authority to the President.