In that speech, Obama said the bulk phone collection program would continue for the time being. He directed the Justice Department and intelligence officials to find ways to end the government's control over the phone data. He also insisting on close supervision by a secretive federal intelligence court and reducing the breadth of phone records the NSA can investigate. Phone companies have said they do not want to take responsibility for overseeing the data under standards set by the NSA.
In addition to concluding that the daily collection of phone records was illegal, the board also determined that the practice was ineffective.
"We have not identified a single instance involving a threat to the United States in which the program made a concrete difference in the outcome of a counterterrorism investigation," it said, and added, "We are aware of no instance in which the program directly contributed to the discovery of a previously unknown terrorist plot or the disruption of a terrorist attack."
It said the NSA should instead seek individual records relevant to terror cases directly from phone service providers under existing laws.
"Given the limited results, we concluded the program should be ended," said board member James Dempsey of the Center for Democracy and Technology, a civil liberties group. Dempsey and another board member, former chief federal appeals court judge Patricia Wald, also said the phone sweeps did not appear to have clear or strong legal grounding in the USA Patriot Act the statute overseeing the government's surveillance activities.
"We have to be careful that secret law does not creep into our jurisprudence," Wald said.
The board wrote that the phone surveillance did not have a "viable legal foundation" under the Patriot Act, which was used to provide legal backing for the operation after it was secretly authorized by President George W. Bush. The board also said the surveillance raised constitutional concerns about unreasonable searches, free speech and freedom of the press. Two federal judges have split in recent rulings over the constitutionality of the government collecting Americans' phone records in such a wholesale way.
The White House disagreed with the oversight board. "The administration believes the program is lawful," said national security spokeswoman Caitlin Hayden. She added that Obama "believes we can and should make changes in the program that will give the American people greater confidence in it."
The board's recommendation to delete its copies of everyone's phone records is one area that Obama sidestepped in his speech what to do with the mountainous electronic database amassed by the NSA since shortly after the 9/11 attacks. National security officials have a legal review to be finished by March should decide how long to keep the phone records.
The NSA's surveillance programs and other data mining operations came to light last year, drawing intense criticism after revelations fueled by an estimated 1.7 million documents taken by former NSA systems analyst Edward Snowden and handed over to several journalists.
During a web chat posted Thursday on the "Free Snowden" site, Snowden echoed the oversight board's skepticism about the phone sweeps as an effective counterterrorism program. Snowden said "it's time to end 'bulk collection,' which is a euphemism for mass surveillance. There is simply no justification for continuing an unconstitutional policy with a 0% success rate."
In its report, the oversight committee's majority said that "we have not identified a single instance involving a threat to the United States in which the program made a concrete difference in the outcome of a counterterrorism investigation."
The oversight board included 11 other recommendations on surveillance policy, calling for more government transparency and other reforms aimed at bolstering civil liberties and privacy protections. The board urged appointment of special attorneys to provide independent views in some proceedings before the secretive spy court, as opposed to Obama's plan for a panel of experts that would participate at times. The board also urged the administration to provide the public with clear explanations of the legal authority behind any surveillance affecting Americans.
Senate Judiciary Committee Chairman Patrick Leahy, D-Vt., said the board's report would "add to the growing chorus calling for an end to the government's dragnet collection of Americans' phone records." Leahy is co-sponsoring a bill that would shut down the phone program.
Civil liberties groups applauded the board's report. "We agree with both its analysis and its principal conclusions," said Jameel Jaffer, deputy legal director of the American Civil Liberties Union. Jaffer has pressed one lawsuit against the government seeking to shut down the bulk phone collections.
While the oversight board found consensus in some of its recommendations for transparency, its members were sharply divided when it came to the surveillance programs and their judicial oversight.
Two members, former Bush administration Justice Department lawyers Rachel Brand and Elisebeth Collins Cook, defended the bulk phone sweeps and said they were too valuable to shut down.
"I am concerned about the detrimental effect this superfluous second-guessing can have on our national security agencies and their staff," said Brand, who as a Justice Department lawyer defended Patriot Act legislation that provided the NSA with its authority to make the bulk phone collections.
But the oversight board's three other members Dempsey, Wald and executive director David Medine held firm for broad changes.
"When the government collects all of a person's telephone records, storing them for five years in a government database that is subjected to high-speed digital searching and analysis, the privacy implications go far beyond what can be revealed by the metadata of a single telephone call," the majority wrote.