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Does Iowa still treat non-impairing trace amounts of THC as per se intoxicated?

Yes. In Iowa, you can actually violate the state’s drunk driving law, called Operating While Intoxicated or, alternatively, Operating While Under the Influence, OWI, by being under the influence, or, impaired by, a drug or a combination of drugs and alcohol. This includes having any amount of THC, the psychoactive ingredient in marijuana, in your blood or urine.


You may only assert a prescription drug defense if you have a valid prescription for the drug in question and you use it according to your physician’s instructions. The jury is still out on how Iowa will treat medical marijuana card holders who are “under the influence” of marijuana because “any amount” of marijuana is enough to be considered under the influence.


In 2017, the Iowa Supreme Court decided State v. Childs, in which an OWI defendant moved to dismiss his DUI by marijuana case because his urine test revealed non-impairing amounts of carboxy-THC.


The State relied on an older decision called Comried wherein the Supreme Court held that any amount means any amount in Chapter 321J, Iowa’s drunk driving law that makes a positive test for any amount of a controlled substance per se impaired.


The first thing the Iowa Supreme Court emphasized in Childs is that the defendant preserved error on, and only argued, statutory interpretation of Iowa’s drunk driving law is no longer valid because the Arizona decision upon which Comried relied was overturned. It is no longer DUI in Arizona to drive with non-impairing levels of THC in a motorist’s urine.


But how does this affect medical marijuana card holders? The Court alluded to that issue, which did not arise in the Childs case.


Justice Mansfield, writing for the Court, noted that “[t]he legislature recently amended the narcotics laws to allow limited medical use of cannabis oil derived from marijuana, but chose to leave intact Iowa Code section 321J.2(1)(c). Childs does not claim he had a valid prescription for medicinal marijuana.” State v. Childs, 898 N.W.2d 177, 182 (Iowa 2017)


The Iowa Supreme Court recounted its decision in Comried, quoting an Arizona case, and noting that “since the manufacture and distribution of illicit drugs are unregulated and because the drugs' potency varies, the effects are unpredictable. Therefore, . . . there is no level of use above which people can be presumed impaired or below which they can be presumed unimpaired.”


It noted that there is no agreed upon over-under level of marijuana in one’s urine that could be used to exonerate a motorist and criminalize a “non-impairing” amount of THC.


It held that the Iowa Legislature “case a wider net,” and finds no quarrel with criminalizing operation of a motor vehicle by marijuana users who have mere trace amounts of marijuana in their urine from some past use.


They disagreed that this interpretation of the law produces “absurd results,” a doctrine that would suggest overruling application of the statute to non-impaired motorists with trace amounts of THC in their urine.


The Court noted that the Iowa Legislatures has made illegal marijuana derived drugs “including tetrahydrocannabinols,” indicating its prohibition extends to “any amount” of controlled substance in Iowa’s drunk driving laws.


The Court therefore upheld the conviction of the driver whose urine showed non-impairing trace amounts of THC.


If you or a loved one have been arrested for Operating While Intoxicated, OWI, or other Iowa criminal offense in Cedar Rapids, Iowa City, or other Iowa community, contact us for a free initial consultation.


Even if a chemical test comes back with "nonimpairing" amounts of THC, Iowa courts consider a motorist "per se," or, automatically, impaired under the State's drunk driving law.

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