Panels are used in contrast to single-judge appeals, and en banc hearings, which involves all of the judges of that court.
In addition, in many countries of the civil law tradition, trial courts are also constituted as judicial panels.
Cases and controversies shall be heard and determined by a court or panel of not more than three judges (except that the United States Court of Appeals for the Federal Circuit may sit in panels of more than three judges if its rules so provide), unless a hearing or rehearing before the court en banc is ordered by a majority of the circuit judges of the circuit who are in regular active service.This practice has been in place since as early as 1891.
Following oral arguments, the judges will meet briefly to confer and determine what the likely majority opinion in the case will be.
In 1963, judge Benjamin Franklin Cameron of the United States Court of Appeals for the Fifth Circuit "threw [the court] into turmoil, charging Chief Judge Elbert P. Tuttle with manipulating the composition of panels in civil rights and desegregation cases so as to influence their outcome".