A federal surveillance court has rejected the Obama administration's bid to hold onto millions of phone records beyond the current five-year limit.
The ruling is a rare rebuke for the government from the secretive Foreign Intelligence Surveillance Court. The court has rejected less than 1 percent of government spying requests over the past 30 years.
But Judge Reggie Walton said he found the Justice Department's argument for extending the retention of phone records "simply unpersuasive."
Government lawyers had argued that they needed to retain the data as evidence for the slew of privacy lawsuits filed in the wake of Edward Snowden's leaks about National Security Agency surveillance. The American Civil Liberties Union, the Electronic Frontier Foundation, and other groups are suing to shut the program down, claiming it violates the constitutional rights of millions of Americans.
In a filing with the court last month, the Justice Department said the government has a "duty to preserve" the phone records that overrides other obligations. The government said it would preserve the data in a format that would prevent NSA analysts from accessing it.
"The United States must ensure that all potentially relevant evidence is retained," the Justice Department wrote in its filing.
But the federal judge noted that none of the privacy groups have tried to force the NSA to hold onto the data for their lawsuits. He wrote that the groups are seeking "the destruction of the [telephone] metadata, not its retention."
Walton concluded that there is no legal requirement for the NSA to retain the data, and that any motivation for retaining the records is outweighed by the privacy harm.
"The amended procedures would further infringe on the privacy interests of United States persons whose telephone records were acquired in vast numbers and retained by the government to aid in national security investigations," he wrote.
The data includes phone numbers, call times, and call durations for millions of U.S. phone calls — but not the contents of any communications.