Maybe not so much. My understanding from talking to a liberal law professor and reading a relevant case is that--contrary to much of the chatter--the constitutionality of the NSA spying is actually unclear. Short explanation: The Supremes has held that the president does not have the power to skip warrants when it comes to domestic threats (think Timothy McVeigh). But in the same case--the "Keith" case, which was decided in 1972-- also explicitly withheld judgment of warrantless spying with regard to agents of foreign powers (think Moussaoui.) The precedent and attendant murkiness is nicely summarized in this 200 U.S. District court ruling:
The Government urges that the searches at issue in this case fall within an established exception to the warrant requirement. According to the Government, searches conducted for the purpose of foreign intelligence collection which target persons who are agents of a foreign power do not require a warrant. The Defendant asserts that such an exception does not exist and should not be recognized by this Court.
The Supreme Court has acknowledged but has not resolved this issue. See United States v. United States District Court (Keith ), 407 U.S. 297, 321- 22 (1972). Circuit courts applying Keith to the foreign intelligence context have affirmed the existence of a foreign intelligence exception to the warrant requirement for searches conducted within the United States which target foreign powers or their agents. See United States v. Clay, 430 F.2d 165, 171 (5th Cir.1970); United States v. Brown, 484 F.2d 418, 426 (5th Cir.1973); United States v. Butenko, 494 F.2d 593, 605 (3d Cir.1974);
United States v. Buck, 548 F.2d 871, 875 (9th Cir.1977); United States v. Truong Dinh Hung, 629 F.2d 908, 913 (4th Cir.1980). . .