One of the interesting questions about marijuana legalization is the effect it might have on alcohol consumption. On one theory, pot and alcohol are substitutes. That is, there’s a certain amount of total demand for psychoactive drugs, so if pot use goes up, alcohol use will go down. That would be a big win, since alcohol use is generally a lot more dangerous than marijuana use.
But if pot and alcohol aren’t substitutes, then you don’t get this benefit. You get the same amount of drunk driving and, since legal pot would be cheaper and more widely used, more stoned driving too. It’s a net negative.
So which is it? No one knows for sure, because marijuana isn’t cheap enough to be a genuine substitute for alcohol anywhere in the country. However, that might change in Colorado if the 
feds don’t interfere with their marijuana legalization initiative. John Ingold of the Denver Post alerts us to a couple of new pieces of research:
Two studies out of the University of Colorado Denver provide hints about what might happen. In a paper soon to be published in the Journal of Law and Economics, professor Daniel Rees finds that traffic fatalities drop when states pass medical-marijuana laws. Rees also reports a drop in alcohol consumed by people ages 20-29 in medical-marijuana states.
Professor Benjamin Crost finds a similar relationship in a paper that argues marijuana use decreases and alcohol use increases after young people hit the legal drinking age. “We should expect that the higher availability of marijuana in Colorado will lead to a decrease in alcohol use among young people,” Crost wrote in an e-mail.
That’s encouraging, but there’s nothing like a real-world test to find out for sure. We may get that soon in Colorado and Washington.
Via Mark Kleiman, whose book, Marijuana Legalization: What Everyone Needs to Know, is a must read if you want to understand more about the pros, cons, and fine points of marijuana use and abuse.
