En banc Information
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.
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 [update]  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. 
The UK Supreme Court has twelve justices, and cases are ordinarily decided by panels of five. However, the Court may sit en banc:
- in cases where the Court is being asked to depart, or may decide to depart from a previous decision;
- in cases of high constitutional importance or great public importance;
- in cases where a conflict between decisions in the House of Lords, Judicial Committee of the Privy Council and/or the Supreme Court has to be reconciled; or
- in cases raising an important point in relation to the European Convention on Human Rights. 
As of January 2017 [update], only one case has been heard en banc, R (Miller) v Secretary of State for Exiting the European Union,  which was heard by eleven justices as there was one judicial vacancy at the time.
The Supreme Court of Japan, which has a total of fifteen justices, ordinarily hears cases in panels of five judges, but is required to hear cases en banc (by the "Grand Bench", 大法廷 daihōtei) when ruling on most constitutional issues, when overturning a previous decision of the Supreme Court, when the five-judge panel is unable to reach a decision, and in other limited cases. 
- Legal Definition of En Banc
- law.com Law Dictionary
- Fed. R. App. P. 35(a).
- Pub.L. 95–486
- See Abebe v. Holder, 577 F.3d 1113 (2009); Compassion in Dying v. Washington, 85 F.3d 1440 (9th Cir. 1996); United States v. Penn, 647 F.2d 876, 889-91 (9th Cir. 1980); Campbell v. Wood, 20 F.3d 1050, 1051, 1053 (9th Cir. 1994).
- Paul Elias (2009-11-25). "Feds seek rehearing of baseball drug list ruling". Associated Press.
- "Feds seek rehearing of baseball drug list ruling". USA Today. 2009-11-24.
- "U.S. Courts of Appeals; Additional Authorized Judgeships" (PDF).
- "TYLER v. HILLSDALE COUNTY SHERIFF'S DEPARTMENT" (PDF).
"IN RE OPINIONS & ORDERS OF THIS COURT ADDRESSING BULK COLLECTION OF DATA UNDER THE FOREIGN INTELLIGENCE SURVEILLANCE ACT" (PDF).
Sitting en banc for the first time in our history, we now vacate that decision.
- Darbyshire, Penny (2015-05-19). "The UK Supreme Court - is there anything left to think about?". European Journal of Current Legal Issues. 21 (1). ISSN 2059-0881.
- Michael Holden (30 November 2016). "Factbox: Brexit case in Britain's Supreme Court – how will it work?". Reuters. Retrieved 24 January 2017.
- "裁判所｜Court System of Japan". www.courts.go.jp (in Japanese). Retrieved 2017-01-25.