Haw. Rev. Stat. § 121-38: Wearing of uniform for private purposes.

Any member of the national guard or other component of the militia wearing a uniform or any portion thereof issued by the United States or the State, except for military purposes, without permission being first obtained from an officer authorized to grant this permission by the governor, is guilty of a misdemeanor, and shall be punishable by a fine not exceeding $25, or imprisonment for not more than thirty days.