Amid the ongoing controversy over the administration's surveillance programs, many are asking to what extent Congress was kept in the loop. Now there's a partial answer: National security officials briefed lawmakers 13 times between 2009 and 2013 about Section 215 of the Patriot Act, according to a senior administration official who spoke on the condition of anonymity because of the classified nature of some of the meetings.

Officials -- including assistant attorney general David Kris, Gen. Keith B. Alexander, commander of the U.S. cyber command, and Todd Hinnen, acting assistant attorney general for national security -- testified at six different hearings about Patriot Act reauthorization. There were two classified meetings, on Nov. 29, 2010 and March 15, 2011. FBI director Robert Mueller spoke about the program in the context of the Patriot Act's 2011 reauthorization in separate briefings in to the House Republican Conference and the House Democratic Caucus, on May 13, 2011 and May 24, 2011, respectively.

And on Feb. 8, 2011, Senate Intelligence Committee Chairman Dianne Feinstein (D-Calif.) and Vice Chairman Saxby Chambliss (R-Ga.) wrote their colleagues to say they could read a classified report on the program.

The content of these closed briefings are hard to judge, of course, since they are out of public view. And when Se, Ron Wyden (D-Ore.) asked Director of National Intelligence James Clapper in March during a hearing whether the National Security Agency collects "any type of data at all on millions or hundreds of millions of Americans," Clapper replied, "No sir. Not wittingly."

In an Oct. 19, 2011, letter to Wyden, assistant attorney general Ronald Welch wrote that the intelligence community is "conducting court-authorized intelligence activities pursuant to a public statute, with the knowledge and oversight of Congress and the Intelligence Committees of both Houses."

"In sum, given the constraints as to what can be discussed in an unclassified setting, we believe that we have been as forthcoming as possible in our discussions of section 215," Welch added.

Not everyone agrees this process provides sufficient accountability. Laura Murphy, who directs the American Civil Liberties Union’s Washington legislative office, said President Obama is aware of the limits of such briefings.

"I think he knew in 2005 what he knows in 2013: the checks on the use of the Patriot Act are inadequate and the [Foreign Surveillance Intelligence Court] often serves as a rubber stamp for the executive branch, and congressional oversight is very limited in terms of the information it receives," Murphy said. "What's the check and balance?"