Really? Where's that the law?
Where is it the law that the byproduct of metabolizing THC is the same as THC? Despite the fact that the court has decreed it so, the two are not the same.
The law in this case was against driving while under the influence. The evidence for marijuana was established to be THC under that law. By fiat, the judiciary has now negated the chemistry that differentiates THC from its metabolized derivative.
The intent of the law, IMO, was to use THC levels to detect the impairment of driving in a measurable manner. The rewriting of the law to include non-impairing derivatives - in direct contradiction of the physical properties of the two substances - is breathtaking.