Haw. Rev. Stat. § 271-15: Dual operation.

Unless, for good cause shown, the public utilities commission finds or has found that both a certificate and a permit may be so held consistently with the public interest and with the declaration of policy declared in this chapter:

(1) No person, or any person controlling, controlled by, or under common control with such person, shall hold a certificate as a common carrier authorizing operation for the transportation of property by motor vehicle within a territory if such person or any such controlling person, controlled person, or person under common control, holds a permit as a contract carrier authorizing operation for the transportation of property by motor vehicle within the same territory; and

(2) No person or any person controlling, controlled by, or under common control with such person, shall hold a permit as a contract carrier authorizing operation for the transportation of property by motor vehicle within a territory, if the person or any controlling person, controlled person, or person under common control, holds a certificate as a common carrier authorizing operation for the transportation of property by motor vehicle within the same territory.