LEX MAJORIS PARTIS

lex majoris partis (leks m<<schwa>>-jor-is pahr-tis). [Latin “law of the major party”] Majority rule. See MAJORITY RULE.

“The voice of the majority decides. For the lex majoris partis is the law of all councils, elections, &c. where not otherwise expressly provided. But if the house be equally divided, ‘semper presumatur pro negante:’ that is, the former law is not to be changed but by a majority.” Thomas Jefferson, A Manual of Parliamentary Practice 105 (1801) (citation omitted).

[Blacks Law 8th]