from
Bouvier's Law Dictionary, Revised 6th Ed (1856)
UNANIMITY. The agreement of all the persons concerned in a thing in design
and opinion.
2. Generally a simple majority (q.v.) of any number of persons is
sufficient to do such acts as the whole number can do; for example, a
majority of the legislature can pass a law: but there are some cases in
which unanimity is required; for example, a traverse jury, composed of
twelve individuals, cannot decide an issue submitted to them, unless they
are unanimous.