The Senate Armed Services Committee broke Senate rules last week when it closed to the public a vote to hold its defense authorization bill markup in closed session.

Before the May 21 markup began, CQ Roll Call discovered the doors to the committee room on the second floor of the Russell Senate Office Building were locked as staffers and senators entered the room through a side office. Inside, all individuals who entered the room were checked for clearance before the vote to close the markup occurred.

Despite the fact that the vote took place behind closed doors, committee chairman Carl Levin, D-Mich., insisted that it was a public vote because the Armed Services Committee publishes the roll call once the markup concludes. Levin’s press secretary Tara Andringa said it would not be practical to open the room to the public for the vote because the Capitol Police must conduct a security sweep of the room before classified information can be discussed, a process that she says can take several hours.

“Once the room is swept, only those with the appropriate security clearance can be in the room,” Andringa said. “To address the Senate rule, the committee releases the result of the vote on whether to close the session.”

But according to the Standing Rules of the Senate, a motion for a committee to go into closed session must be “followed immediately by a record vote in open session.”

The decision to close the vote comes at a time when the committee has already faced criticism from reporters and transparency advocates for holding its defense authorization markup in closed session while the House Armed Services Committee holds its version in public.

“I can’t imagine why they close even the vote to close it. That just seems ridiculous,” said Melanie Sloan, executive director of Citizens for Responsibility and Ethics in Washington. “And if they’re not marking up classified information, the real question is why any of it shouldn’t be opened up to the public.”

The opinion is even shared by several members of the committee. This year, eight senators voted against closing the NDAA markup: Claire McCaskill, D-Mo.; Jeanne Shaheen, D-N.H.; Kirsten Gillibrand, D-N.Y.; Richard Blumenthal, D-Conn.; Kelly Ayotte, R-N.H.; David Vitter, R-La.; Mike Lee, R-Utah; and Ted Cruz, R-Texas.

Levin also defended the practice of closing the markup as a matter of practicality that prevents the committee form having to repeatedly clear the room whenever classified material is brought up. He told CQ Roll Call that the committee discussed classified information twice during last week’s markup. However the House Armed Services Committee completed its NDAA markup earlier this month without discussing classified information at all.

“We’ve been long concerned about the lack of public participation allowed in this process,” said Angela Canterbury, director of public policy at the Project on Government Oversight. “We think that the claims of national security concerns are quite overblown because naturally the House is able to segregate the small amount of classified information that’s in the NDAA and deal with the vast majority of the bill in a completely open process. So why can’t SASC?”

Even John McCain, R-Ariz., who was among the 18 senators to vote in favor of closing the markup, acknowledges that his vote was not an endorsement of Levin’s concerns

“I don’t think it’s necessary, but I also have the greatest respect for Sen. Levin,” McCain said. “We’ve worked together for many years, and that’s his desire. I understand the frustration that provides people like you, and I’m sorry.”

He also hinted that he expects the committee to more seriously revisit the issue during next year’s NDAA markup, after Levin’s retirement. McCain has expressed interest in chairing the Armed Services Committee if Republicans can capture the Senate in November.

The only time the full committee has opened its NDAA markup to the public under Levin was in 2013, when it held two hours of public discussion on the bill’s sexual assault provisions. But the practice predates the current chairman, who took over the role in 2007. Between 1997 and 2010, all Senate committee and subcommittee NDAA markups were held in closed session. Since then, the committee has opened up some subcommittee meetings on the authorization bill, including three of this year’s six subcommittee markups.