Haw. Rev. Stat. § 271-29: Identification of carriers.

The public utilities commission is authorized, under such rules and regulations as it shall prescribe, to require the display of suitable identification number or numbers, upon any motor vehicle used in transportation subject to this chapter, and to provide for the issuance of numbers. Any substitution, transfer, or use of any identification number or numbers, except such as may be duly authorized by the commission, is prohibited and shall be unlawful.