## Facts

- Michael Bernard Harris was stopped during a routine traffic stop.
- Harris admitted he had used marijuana the prior night.
- A blood test detected only carboxy-tetrahydrocannabinol (carboxy-THC/CTHC), an inactive marijuana metabolite that can remain in the body for weeks and does not cause impairment.
- The record distinguished CTHC from hydroxy-tetrahydrocannabinol (HTHC), an intoxicating metabolite that appears for a relatively short time after use before converting into CTHC.
- The State charged Harris with (1) impairment-based DUI under A.R.S. § 28-1381(A)(1) and (2) per se drug DUI under A.R.S. § 28-1381(A)(3) for driving with THC “or its metabolite” in his body.
- Harris moved to dismiss the (A)(3) charge, arguing the statute did not reach a driver whose blood contains only CTHC and not THC or an impairing metabolite such as HTHC.
- The trial court dismissed the (A)(3) count; the superior court left that dismissal in place; the court of appeals reversed; the Arizona Supreme Court granted review.

## Issues

1. Does “its metabolite” in A.R.S. § 28-1381(A)(3) include an inactive, non-impairing marijuana metabolite such as carboxy-THC, or is the statute limited to THC and impairing metabolites?

## Decision

- The Arizona Supreme Court reversed the court of appeals and affirmed the dismissal of the (A)(3) charge.
- The court held that A.R.S. § 28-1381(A)(3) reaches THC and impairing metabolites (such as HTHC), but not inactive, non-impairing metabolites like carboxy-THC.
- Because Harris’s blood contained only carboxy-THC, the State did not allege a substance that satisfies § 28-1381(A)(3) as construed by the court.

## Legal Principles

- Statutory terms must be read in context and in light of the statute’s function; where a term can reasonably bear more than one meaning, courts consider structure, purpose, and consequences of competing readings.
- Interpreting § 28-1381(A)(3) to criminalize driving based solely on long-lasting, non-impairing metabolites would punish conduct that has no proven connection to impaired driving and would yield unreasonable results.
- The DUI scheme targets impaired driving and also creates certain per se offenses tied to substances that indicate present impairment risk; a reading of “metabolite” limited to active, impairing metabolites aligns with that aim.
- When lingering ambiguity remains in a criminal statute after using standard interpretive tools, the rule of lenity requires the court to choose the narrower interpretation favoring the defendant.
- Under § 28-1381(A)(3), proof that a defendant has only inactive carboxy-THC in the body is insufficient; the statute requires the presence of THC itself or an active, impairing metabolite.

## Conclusion

Arizona ex rel. Montgomery v. Harris holds that A.R.S. § 28-1381(A)(3) does not make it a crime to drive with only carboxy-THC in one’s body because that metabolite is inactive and not linked to impairment; the per se drug DUI provision applies to THC and metabolites capable of causing impairment, so dismissal of the (A)(3) charge was proper where the blood test showed only carboxy-THC.


Arizona ex rel. Montgomery v. Harris, 322 P.3d 160, 234 Ariz. 343 (2014)