In law, an en banc session (French for "in bench") is a session in which a case is heard before all the judges of a court (before the entire bench) rather than by a panel of judges selected from them.The equivalent terms in banc, in banco or in bank are also sometimes seen. En banc review is often used for unusually complex cases or cases considered to be of greater importance.
Appellate courts in the United States sometimes grant rehearing en banc to reconsider a decision of a panel of the court (typically consisting of only three judges) in which the case concerns a matter of exceptional public importance or the panel's decision appears to conflict with a prior decision of the court.In rarer instances, an appellate court will order hearing en banc as an initial matter instead of the panel hearing it first.
The Supreme Court of the United States, and the highest courts of most states, do not sit in panels but hear all of their cases en banc (with the exception of cases where a judge is ill or recused).
Cases in United States courts of appeals are heard by a three-judge panel. A majority of the active circuit judges may decide to hear or rehear a case en banc. Parties may suggest an en banc hearing to the judges but have no right to it. The Federal Rules of Appellate Procedure state that en banc proceedings are disfavored but may be ordered to maintain uniformity of decisions within the circuit or if the issue is exceptionally important (Fed. R. App. P. 35(a)). Each court of appeals also has particular rules regarding en banc proceedings. Under the doctrine of stare decisis, as applied in the federal court system, only a court sitting en banc or the U.S. Supreme Court can overrule a prior decision in the same circuit; in other words, one panel cannot overrule another.
Federal law provides that for courts with more than 15 judges, an en banc hearing may consist of "such number of members of its en banc courts as may be prescribed by rule of the court of appeals."The Ninth Circuit, with 29 judges, uses this procedure, and its en banc court consists of 11 judges. Theoretically, the Ninth Circuit can hear the case with all judges participating. In practice, however, such a hearing has only been requested rarely; the requests have all been denied. The Fifth Circuit, with 17 judges, also adopted a similar procedure in 1986. State of La. ex rel. Guste v. M/V TESTBANK, 752 F.2d 1019 (5th Cir. 1985) (en banc). The Sixth Circuit has 16 judges but as of September 2016 it has not yet adopted such a policy; en banc cases are generally heard by all 16 judges. The Foreign Intelligence Surveillance Court, established in 1978, sat en banc for the first time in 2017 in a case concerning bulk data collection. https://en.wikipedia.org/wiki/En_banc