Wyo. Const. art. 1, § 9: Trial by jury inviolate.

The right of trial by jury shall remain inviolate in criminal cases. A jury in civil cases and in criminal cases where the charge is a misdemeanor may consist of less than twelve (12) persons but not less than six (6), as may be prescribed by law. A grand jury may consist of twelve (12) persons, any nine (9) of whom concurring may find an indictment. The legislature may change, regulate or abolish the grand jury system.