State ex rel. Montgomery v. Harris
The Arizona Supreme Court determined the term "its metabolite" was ambiguous because it could include "all of a proscribed drug's byproducts" or only "primary or impairment-causing metabolites." 234 Ariz. 343,11-12, 346 P.2d at 987.
It concluded that adopting the first interpretation--the term "its metabolite" encompassed all byproducts--would lead to an absurd result because it would "criminalize otherwise legal conduct," "a driver who tested positive for trace elements of a non-impairing substance could be prosecuted," and legal substances could generate metabolites common with prohibited substances. Id.14-17.
Based on the statute's intent--"to prevent impaired driving"--the court thus "held that the 'metabolite' reference in 28-1381(A)(3) is limited to any of a proscribed substance's metabolites that are capable of causing impairment." Id.24.