I can only quote:
”“Mr. Blunt stated that members in the Minority believe they have information relevant to the debate on FISA that cannot be publicly discussed,” Hoyer said. “The majority agreed to Mr. Blunt’s request so that the Members may hear this information in a secret session that will proceed for one hour.”
A closed session would require at least three hours for security personnel to sweep the chamber for listening devices.
“All of our members need to hear and have a chance to think about this information,” said Blunt
House Judiciary Committee Chairman John Conyers Jr. (D-Mich.) said he was skeptical the closed session would change any minds on the issue and may end up costing the Republicans support.
“As someone who has chaired classified hearings and reviewed classified materials on this subject, I believe the more information members receive about this administration’s actions in the area of warrantless surveillance, the more likely they are to reject the administration’s scare tactics and threats.””
http://www.politico.com/blogs/thecrypt/0308/House_to_go_into_rare_closed_session.html