This June 6, 2013 file photo shows the sign outside the National Security Agency campus in Fort Meade, Md.  (AP Photo/Patrick Semansky)

The National Security Agency recently used a novel argument for not holding onto information it collects about users online activity: it's too complex.

The agency is facing a slew of lawsuits over its surveillance programs, many launched after former NSA contractor Edward Snowden leaked information on the agency's efforts last year. One suit that pre-dates the Snowden leaks, Jewel v. NSA, challenges the constitutionality of programs that the suit allege collect information about American's telephone and Internet activities.

In a hearing Friday, U.S. District  for the Northern District of California Judge Jeffrey S. White reversed an emergency order he had issued earlier the same week barring the government from destroying data that the Electronic Frontier Foundation had asked be preserved for that case. The data is collected under Section 702 of the Amendments Act to the Foreign Intelligence Surveillance Act.

But the NSA argued that holding onto the data would be too burdensome. "A requirement to preserve all data acquired under section 702 presents significant operational problems, only one of which is that the NSA may have to shut down all systems and databases that contain Section 702 information," wrote NSA Deputy Director Richard Ledgett in a court filing submitted to the court.

The complexity of the NSA systems meant preservation efforts might not work, he argued, but would have "an immediate, specific, and harmful impact on the national security of the United States." Part of this complexity, Ledgett said, stems from privacy restrictions placed on the programs by the Foreign Intelligence Surveillance Court.

"Communications acquired pursuant to Section 702 reside within multiple databases contained on multiple systems and the precise manner in which NSA stays consistent with its legal obligations under the [FISA Amendments Act] has resulted from years of detailed interaction" with the Foreign Intelligence Surveillance Court and the Department of Justice, Ledgett wrote. NSA regularly purges data "via a combination of technical and human-based processes," he said.

The government's explanation raises more concerns, said Cindy Cohn, EFF's legal director. "To me, it demonstrates that once the government has custody of this information even they can't keep track of it anymore even for purposes of what they don't want to destroy," she said in an interview.

"With the huge amounts of data that they're gathering it's not surprising to me that it's difficult to keep track-- that's why I think it's so dangerous for them to be collecting all this data en masse," Cohn added.

The debate over preserving data for the lawsuit puts EFF in the odd position of  arguing that the government should retain data the group ultimately wants destroyed. 

According to Cohn, EFF discovered the issue by accident: An e-mail exchange with a Justice Department lawyer last week revealed that the government was looking into whether it could preserve data collected under 702 programs. That was surprising, she said, because the NSA had previously been ordered to preserve the data related to the suit, including an initial preservation order in 2009 and temporary restraining order in March.

But it's unclear just how much of the data EFF seeks has already been destroyed. In a brief filed with the court in May, EFF said there was "no doubt" that the government had already destroyed evidence related to the claims. 

The government has argued that the case, which was filed in 2008, should be thrown out and that Section 702 programs do not target Americans so it is "highly unlikely" that the plaintiffs communications were acquired through those programs. EFF disputes that argument.