Generally revise driving under the influence laws for THC levels in drivers under 21

This bill amends Montana's driving under the influence laws to establish that any detectable amount of THC in a driver's body constitutes a DUI offense for individuals under 21 years of age. The legislation specifically targets drivers under 21 by removing any previous threshold for THC levels, meaning even trace amounts of the substance would be illegal to drive with. The change applies to noncommercial vehicles and excludes inactive metabolites from the calculation, focusing only on active THC present in the bloodstream or other bodily substances. This provision creates a zero-tolerance policy for underage drivers regarding cannabis use while operating a vehicle, without altering the existing DUI standards for drivers 21 and older.