Haw. Rev. Stat. § 803-5: By police officer without warrant.

(a) A police officer or other officer of justice, may, without warrant, arrest and detain for examination any person when the officer has probable cause to believe that such person has committed any offense, whether in the officer's presence or otherwise.

(b) For purposes of this section, a police officer has probable cause to make an arrest when the facts and circumstances within the officer's knowledge and of which the officer has reasonably trustworthy information are sufficient in themselves to warrant a person of reasonable caution in the belief that a crime has been or is being committed.