While medical marijuana advocates will politely ask them to stop talking whenever the subject arises, there are many cannabis users who will claim that the task of operating a motor vehicle is safer when the driver is a bit stoned.
Turns out that researchers crunching traffic data from 13 states -- including car- and cannabis-crazy California -- arrived at a similar conclusion, only with an extra hitch: Drivers in states with medical marijuana laws are not only safer, they're more sober.
A 9 percent drop in traffic fatalities and a 5 percent drop in beer sales were observed in states where cannabis is legal, according to a study conducted by economics professors at the University of Colorado-Denver and Montana State University.
Something to consider: Traffic deaths are the leading cause of death among Americans ages five to 34, and as MADD reminds us, drinking-and-driving-related fatalities affect even the sober. So medical marijuana makes the roads safer for everyone.
The study is believed to be the first examination of the relationship between traffic deaths and legalized marijuana, according to study's authors, Daniel Rees, professor of economics at the University of Colorado Denver, and D. Mark Anderson, professor of economics at Montana State University. That in itself shocked the study's authors.
"We were astounded by how little is known about the effects of legalizing medical marijuana," Rees said. "Although we make no policy recommendations, it certainly appears as though medical marijuana laws are making our highways safer."
The study by no means condones the one-hand-blunt-rolling method performed while changing lanes. Rather, it observes that such behavior is unlikely: Drivers who use alcohol are more likely to take risks, while drivers using marijuana avoid risks.
In fact, they might avoid driving altogether. Most medical marijuana is consumed at home, while alcohol is consumed at bars and restaurants, according to the study.
There's also a correlation between beer sales and medical marijuana laws: 20-to-29-year-olds buy less beer when they live in states with legal cannabis, according to figures provided by the Beer Institute. That makes the alcohol industry's opposition to Proposition 19 last year a little less mysterious. Less alcohol on the roads means less danger on the roads, hence the 9 percent drop in fatalities.
The study also looks at the oft-repeated claims of marijuana prohibition supporters that legal pot causes an increase in criminal activity (which was always dubious) and that medical marijuana leads to increased use among minors. The authors concluded that "no evidence to support [either] hypothesis" could be found.
So find the car with the Bob Marley sticker and follow it home. Just be careful when you drive past the bar.
Follow us on Twitter at @TheSnitchSF and @SFWeekly