Legal sources say the tiny courtroom and adjacent areas are sealed tightly -- ironically, given the political debate -- to prevent any eavesdropping by outsiders.
Eleven federal judges from around the country serve on the court for seven-year terms. They are appointed by the chief justice of the United States.
John Roberts has named all current members, as a well as a three-judge panel that hears appeals of FISA orders, known as the Court of Review.
Also addressing the privacy board Tuesday were two former Bush administration officials, Steven Bradbury and Kenneth Wainstein, who defended the government surveillance programs.
Bradbury said the NSA program has "multiple levels of oversight" in all three branches of government. He said the metadata requests helped isolate terror operations both in the United States and overseas.
And Wainstein said Robertson's suggestion of a legal adversary in FISA court proceedings would be a "recipe for disaster" because of the sensitivity of the information surrounding a terrorism or national security investigation.