[§286-158.5] Interpretation of drug tests; competent evidence. In any criminal prosecution or civil proceeding relating to section 291-7, the presence of any drug that impairs a person's ability to operate a vehicle in a careful and prudent manner within three hours after the time of the alleged offense, as shown by chemical analysis or other approved analytical techniques of the defendant's blood or urine, shall be competent evidence that the defendant was under the influence of drugs at the time of the alleged violation. Nothing in this section shall be construed as limiting the introduction, in any criminal proceeding for a violation under section 291-7 or in any proceeding under section 286-157.4, of relevant evidence of a person's drug content obtained more than three hours after an alleged violation; provided that the evidence is offered in compliance with the Hawaii rules of evidence. [L 1997, c 103, pt of §1]