Haw. Rev. Stat. § 486-134: Optional licensing.

The following persons shall not be required, but shall be permitted, to obtain licenses as public measuremasters:

(1) A law enforcement or measurement standards officer, or other qualified employee of a state or county agency or institution when acting within the scope of the officer's or employee's official duties;

(2) A person weighing property, produce, commodities, or articles that the person, or the person's employer, is either buying or selling; and

(3) A person weighing property, produce, commodities, or articles in conformity with the requirements of federal statutes or the statutes of this State relative to warehouse workers or processors.