U.S. government legal opinions that interpret the powers that the FBI has to conduct surveillance should be declassified and released to the public, a civil liberties group said.
In a report set for release on Tuesday, the American Civil Liberties Union said the proliferation of secret legal interpretations threatened the rights of U.S. citizens to be free from warrantless government searches.
The ACLU launched the criticism just as new FBI Director James Comey settled in at the bureau charged with preventing militant attacks and investigating major U.S. crimes.
The report listed numerous complaints against the expansion of the FBI's authority during the 12 years since the Sept. 11 attacks on New York's World Trade Center and the Pentagon.
"There is already substantial evidence that the FBI has gravely misused its new authorities and capabilities," the report said. The ACLU gave an advance copy to Reuters.
An FBI spokesman said the bureau had not read the report and would not comment until it had. Law enforcement officials have repeatedly said that their programs, including surveillance operations, comply with federal law and are essential to preventing attacks on U.S. citizens.
Among the legal opinions the ACLU wants to see are those that interpret Section 215 of the Patriot Act, the provision used to justify the massive database of telephone call records revealed by former National Security Agency contractor Edward Snowden, and a Justice Department legal opinion from 2010 about the FBI's power to obtain electronic communications records.
Snowden's leaks of secret documents to newspapers sparked a worldwide debate beginning in June about the U.S. government's surveillance capabilities and led some U.S. lawmakers to consider reining in the FBI and other agencies.