Kurt Opsahl of the Electronic Frontier Foundation says,
Today, Judge Ann Aiken of the Oregon Federal District Court ruled that two provisions of the Foreign Intelligence Surveillance Act (FISA), "50 U.S.C. §§ 1804 and 1823, as amended by the Patriot Act, are unconstitutional because they violate the Fourth Amendment of the United States Constitution."
This case arose over warrantless surveillance of an innocent Oregon attorney who was falsely suspected of involvement with the Madrid train bombing based on a mistaken fingerprint identification.
The critical legal issue was that in the Patriot Act, Congress amended FISA to change the language from requiring "the purpose" of the search or surveillance be to obtain foreign intelligence information to only "a significant purpose" of the search or surveillance.
As EFF has previously explained in a case before the Foreign Intelligence Surveillance Court of Review, a "long line of court of appeals decisions, before and after FISA, has held that surveillance may be conducted without a traditional warrant and probable cause only when foreign intelligence collection is the "primary purpose" of the surveillance," not merely a "significant purpose."
The entire text of the court's decision is here (PDF). This is the really churchy part, on pages 43-44:
For over 200 years, this Nation has adhered to the rule of
law - with unparalleled success. A shift to a Nation based on
extra-constitutional authority is prohibited, as well as ill-
advised. In this regard, the Supreme Court has cautioned:
The price of lawful public dissent must not be a
dread of subjection to an unchecked surveillance
power. Nor must the fear of unauthorized official
eavesdropping deter vigorous citizen dissent and
discussion of Government action in private conversation.
For private dissent, no less than open public
discourse, is essential to our free society.