Haw. Rev. Stat. § 281-80: Arrest.

Any investigator or police officer who observes any violation by any person of this chapter or of any rule or regulation of the liquor commission, may forthwith arrest the person without a warrant. Whenever any violation of this chapter or of the regulations of the commission occurs in the presence of any licensee, or any investigator or police officer, upon request of the licensee the police officer or investigator may assist the licensee in arresting any patron for violation thereof.