James R. Clapper Jr., the director of national intelligence, has acknowledged that the court found the NSA in breach of the Fourth Amendment, which prohibits unreasonable searches and seizures, but the Obama administration has fought a Freedom of Information lawsuit that seeks the opinion.
Generally, the NSA reveals nothing in public about its errors and infractions. The unclassified versions of the administration's semi-annual reports to Congress feature blacked-out pages under the headline, "Statistical Data Relating to Compliance Incidents."
Members of Congress may read the unredacted documents, but only in a special secure room and are not allowed to take notes. Fewer than 10 percent of lawmakers employ a staff member who has the security clearance to read the reports and provide advice about their meaning and significance.
The limited portions of the reports that can be read by the public acknowledge "a small number of compliance incidents."
Under NSA auditing guidelines, the incident count does not usually disclose the number of Americans affected.
"What you really want to know, I would think, is how many innocent U.S. person communications are, one, collected at all, and two, subject to scrutiny," said Julian Sanchez, a research scholar and close student of the NSA at the Cato Institute.
The documents provided by Snowden offer only glimpses of those questions. Some reports make clear that an unauthorized search produced no records. But a single "incident" in February 2012 involved the unlawful retention of 3,032 files that the surveillance court had ordered the NSA to destroy, according to the May 2012 audit. Each file contained an undisclosed number of telephone call records.
One of the documents sheds new light on a statement by NSA Director Keith Alexander last year that "we don't hold data on U.S. citizens."