Hawaii Revised Statutes Division 1. Government § 286-73

The use of any cover or shield installed over a vehicle's license plate, regardless of transparency or intent, shall be prohibited.  Any person who violates this section shall be fined no less than $500 and no more than $1,000 for each offense.  Each day of violation shall constitute a separate offense.  For the purposes of this section, “cover” or “shield” means any device, material, or film-whether clear, tinted, mirrored, reflective, or otherwise that is installed over or affixed to a license plate, and is intended to alter or interfere with the visibility, legibility, or identification of the license plate by law enforcement or traffic enforcement systems.