The National Security Agency's bulk collection of telephone calling records undermines the freedom of the press by chilling potential sources of information from co­operating with reporters, more than a dozen journalistic organizations, including The Washington Post, argued in a legal brief filed Monday in federal court.

“Many significant pieces of American journalism have relied heavily on confidential sources,” said the amicus brief, filed in U.S. District Court in San Francisco. “When the risk of prosecution reaches such sources, quality reporting is diminished. Since the public has become aware of the call tracking, many reporters at major news outlets have said that this program and other NSA surveillance efforts have made sources less willing to talk with them, even about matters not related to national security.”

The brief , organized by the Reporters Committee for the Freedom of the Press, supports a lawsuit filed in July by the Electronic Frontier Foundation, a civil liberties group based in San Francisco, on behalf of more than 20 groups representing environmentalists, gun makers and religious groups. The suit argues that the NSA’s surveillance programs amount to a violation of the constitutional freedom of association and calls for an end to the bulk collection of telephone records.

Signing the amicus brief were 13 journalistic organizations, including the Los Angeles Times, the McClatchy company, the E.W. Scripps Company, the American Society of News Editors, the Society for Professional Journalists and the Newspaper Guild. Also filing an amicus brief in the case Monday were Sens. Ron Wyden (D-Oregon), Mark Udall (D-Colorado) and Martin Heinrich (D-N.M.).

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