banc

[OF. banc, LL. bancus. See Bank, n.]
A bench; a high seat, or seat of distinction or judgment; a tribunal or court.

In banc, In banco (the ablative of bancus), In bank, in full court, or with full judicial authority; as, sittings in banc (distinguished from sittings at nisi prius).

[French, Bench.] The location where a court customarily or permanently sits.

When a court is sitting in banc (or en banc), it means that a meeting or session of all the judges of a court is taking place. The usual purpose of sitting in banc is to hear arguments on demurrers or motions for a new trial.