Cully Stimson writes for the Heritage Institute: “Colorado traffic fatalities have gone down since 2007, but they went up in 2012. More to the point, Colorado traffic fatalities between 2007 and 2012 involving operators testing positive for marijuana use increased 100 percent over that period—from 39 in 2007 up to 78 in 2012.” He helpfully adds, “Of course, we have no idea what actually caused those fatalities.” Often people who test positive for marijuana consumed it long enough ago that they’re no longer under the drug’s influence. And often people who test positive for marijuana also test positive for alcohol and other substances. I’d also like to know whether police are simply reporting marijuana levels more diligently—something that would hardly be surprising given the heated politics surrounding the issue. But even if it is the case that marijuana consumption is a causal factor in more traffic wrecks, that doesn’t mean marijuana should be banned or more heavily regulated—any more than the fact that alcohol consumption is a causal factor in many traffic wrecks means that alcohol should be banned or more heavily regulated. The principle is that government ought not violate the rights of people who use something responsibly (whether guns or drugs or magnets or whatever) because a minority use that thing irresponsibly.