the whole "threat to others/driving under the influence" thing should have no bearing on nthis discussion, imo, because people are already doing it. I don't just mean alcohol, or pot, etc, but anti-anxiety meds, anti-depression meds, uppers (add meds, for example), downers (valium, etc)...
these are all things with warnings on that say "know how this medication affects you before operating a motor vehicle or heavy machinery". if it's good enough for them, why not for coke, or pot, or what-have-you? everyone's metabolism and chemistry is different, so put the onus on the individual to monitor themselves (as it is with current prescription meds) and let people have a choice about what they want to do.
the combination of reclaiming the funding for the ads/promo stuff for the "war on drugs", combined with the hefty taxes one could assign a recreational drug of this nature would go a long way to solving a lot of budget woes.
again, just my opinion...