Driving while intoxicated is never acceptable. The number of deaths that have been attributed to operating an automobile while drunk is heinous. While I like to think that times have changed, and it has become more acceptable to find a different way home from the bar besides using the car you drove ("Bro, I am sooooo wasted. Call me an Uber before I puke the Moscow Mules I drank all over my new Sperry's!"), there is still a dearth of viable options depending on where you get wasted.
Lots of people claim that instead of a detriment, driving after smoking marijuana is actually beneficial to their abilities. One might think that is true — a bit like how alcohol first deteriorates your judgment — but it is not. Unless, maybe, you just happen to be a really shitty, crazy-fast driver and smoking weed is the only thing that slows you down. If that is the case, please reconsider your demonic need for speed.
There has yet to be much of a deterrent to curb smoking weed while driving. The only way to determine whether someone is high behind the wheel is a blood test, and, as we all know, THC blood concentration is measurable long after the effects have worn off. Weed's increasing prevalence and difficulty to objectively determine its ramifications has been a growing problem for law enforcement.
Now, a company is preparing to bring a roadside breathalyzer for marijuana to the market. Oakland, California's Hound Labs has been working with UC Berkeley scientists to measure your breath's THC levels — accurate to one trillionth of a gram. They are being close-chested about the technology involved, but admit it will not measure levels in your bloodstream.
I am not sure whether to be happy or sad about this half-baked method of testing. On one hand, it seems like you will get busted only if you have smoked recently. On the other, it seems like it then must be easily beaten, so in effect— nevermind, just do not get behind the wheel if you are fucked up, and give me a call instead, okay?