Very enlightening. The part on the Cold War is very interesting.

The link is too long to cut&paste but is quoted ehre directly from a pdf file at the ALA page on The Patriot Act:

"CRS-2
In fact, the American Library Association (ALA) Council has recently adopted a resolution that, among other things, declares that the ALA “considers sections of the USA
PATRIOT Act . . . a present danger to the constitutional rights and privacy rights of library users and urges the United States Congress to: 1. provide active oversight to the implementation of the USA PATRIOT Act and other related measures . . . and 3. amend or change the sections of these laws and the guidelines that threaten or abridge the rights of inquiry and free expression. . . .” Resolution on the USA Patriot Act and Related Measures That Infringe on the Rights of Library Users (Jan. 29 2003), available at
[http://www.ala.org].
The sensitivity of the library community may be attributable in part to its experience with a past investigative program of the Federal Bureau of Investigation (FBI). Beginning
in the early 1960's, Soviet intelligence services apparently sought to systematically collect unclassified information available in U.S. libraries, particularly scientific and other
technical libraries. The practice seems to have included research by Soviet agents and the employment of innocent university students to do the research. In order to keep
abreast of Soviet activities, the FBI solicited the assistance of librarians in the institutions that might be targeted by the Soviets and formalized the approach at least in the New York area as the Library Awareness Program. When the program’s existence came to light, the library community objected vehemently, and the program was apparently
dropped, see generally, FBI Counterintelligence Visits to Libraries: Hearings Before the Subcomm. on Civil and Constitutional Rights of the House Comm. on the Judiciary, 100th Cong., 2d Sess. (1988); The FBI's Library Awareness Program: Is Big Brother Reading Over Your Shoulder? 65 NEW YORK UNIVERSITY LAW REVIEW 1532 (1990).
Legal Environment: The FBI has authority to conduct both criminal and foreign intelligence investigations, 28 U.S.C. 533-535; 28 C.F.R. §0.85. The judges of the Foreign Intelligence Surveillance court, assigned from elsewhere on the federal bench to a court established under the Foreign Intelligence Surveillance Act (FISA), may authorize
FBI agents conducting a foreign intelligence investigation to wiretap, conduct physical searches, or use pen registers or trap and trace devices (instruments to secretly identify the source and addressees of telephone calls made to and from a particular telephone), 50 U.S.C. 1801-1846. The FBI enjoys similar judicially-assisted, investigative powers in
criminal cases, 18 U.S.C. 2510-2522, 2701-2708, 3121-3127. In addition, without recourse to the courts, the FBI in foreign intelligence cases may issue so-called national
security letters (NSL) demanding a limited amount of customer identifying information from communications, financial, and credit reporting concerns, 18 U.S.C. 2709, 12 U.S.C. 3414, 15 U.S.C. 1681.
Although the library community stoutly defends the importance of library-patron confidentiality, federal law has yet to recognize its privileged status, F.R.Evid. 501; 22
WRIGHT & GRAHAM, FEDERAL PRACTICE AND PROCEDURE: EVIDENCE, §§5430, 5431 (1980 & 2002 Supp.)(nevertheless suggesting that a limited research privilege akin to a
newsman’s privilege might some day be recognized). Notwithstanding any intrusion upon library-patron confidentiality, as a general rule libraries and librarians must comply with federal grand jury subpoenas, federal search warrants, and other federal court orders.
Moreover, federal investigators are free to request and receive any assistance from libraries and librarians that they are willing to provide.