Definition taken from IN RE: Michael PALMISANO (1995) (http://caselaw.findlaw.com/us-7th-circuit/1463787.html
Although a district court usually acts through single judges, 28 U.S.C. § 132(c) permits the court to sit in panels, or en banc, when a local rule so provides. The Executive Committee in the Northern District of Illinois comprises the court's chief judge and four others who serve for overlapping four-year terms. N.D.Ill.R. 1.02.E. Such a panel is entitled to enter judicial orders.
This appears to be a District Court action, taken after an inquiry from the Circuit itself.