The National Security Agency is making an ironic excuse for why it can’t stop deleting data evidence that could be used against it, despite receiving multiple court orders to stop – it doesn’t know how.

Technology focused privacy group Electronic Frontier Foundation, which currently has a case pending against NSA alleging the agency illegally intercepted client data, discovered through a Justice Department email slip-up last week that the agency was deleting evidence it had already been ordered to keep by multiple courts.

After failing to comply with an order to retain data collected under both executive authority and Foreign Intelligence Surveillance Act authority, DOJ claimed in March it misunderstood the order to read it only had to keep data acquired under the former. Pointing to documents proving otherwise, a FISA Court judge accused the department of attempting to mislead the court, and again ordered the retention of data in both circumstances.

Upon learning the destruction of such data was still going on, EFF immediately filed a restraining order against NSA and DOJ, which California U.S. District Judge Jeffrey White issued against the government the same day along with a demand for an immediate explanation from the government for violating the March order.

The signals intelligence agency responded with a request for the court to immediately overturn its order, and that failing to do so would force the agency to shut down a significant portion of NSA’s surveillance apparatus.

“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,” NSA Deputy Director Richard Ledgett wrote in the agency’s response, along with its intention to file a follow-up explanation.

According to Ledgett, NSA systems are too complex for such a request, and following through with the court’s order would have “an immediate, specific, and harmful impact on the national security of the United States.”

“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 FISA Court and the Department of Justice.

The agency only successfully destroys data “via a combination of technical and human-based processes,” Ledgett wrote.

EFF legal director Cindy Cohn said the agency’s explanation raises even more concerns over NSA’s bulk surveillance programs, and furthers its case against them.

“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,” Cohn said in a Washington Post report. “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.”

It’s unknown how much of the data EFF was counting on for evidence has been destroyed, but the organization has “no doubt” that data related to its claims have been erased.

The government argues that EFF’s 2008 case, Jewel v. NSA, should be thrown out anyway. According to NSA and DOJ, FISA authority programs do not target Americans, and it’s “highly unlikely” that EFF plaintiff communications were intercepted.

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