In a letter to two Senators, the Obama administration has refused to publicly disclose the extent of government tracking of American citizens—or even to describe the legal basis on which it is conducting such tracking. "We will get back to you," the letter says.

Ron Wyden (D-OR) and Mark Udall (D-CO) have emerged in recent months as the Senate's leading critics of unfettered government surveillance. In mid-July, they sent a letter to Director of National Intelligence James Clapper seeking information about whether the federal government had "the authority to collect the geolocation information of American citizens for intelligence purposes." They also asked about the number of Americans whose communications have been intercepted (FISA warrants are only supposed to target non-Americans) and details on rumored incidents of intelligence officials failing to comply with the law.

In a Tuesday letter, Clapper aide Kathleen Turner politely brushed aside all of these questions. She refused to publicly divulge any details about the nature, extent, or legal basis of the government's domestic spying activities. Instead, she directed Wyden and Udall to classified materials the administration had already made available to members of Congress, and offered to discuss the Senators' concerns in greater detail in a classified briefing.

Turner claimed that it was "not reasonably possible to identify the number of people located in the United States whose communications may have been reviewed" under the FISA Amendments Act, though she noted that statistics about the number of "disseminated intelligence reports" containing information about Americans was available in classified materials. Similarly, she argued that she couldn't provide any details about "compliance incidents" without compromising confidential sources and methods.

These responses are remarkable because the Senators were not seeking operational details of the government's surveillance activities. For example, on the subject of geolocation data, they simply asked whether the government believed it had the authority to collect such information, and if so what the basis of that authority was. It's hard to see what justification there could be for keeping secret not just how the government was using its surveillance powers but whether it believed it had such powers at all.