 Opinions on marijuana legalization range from regarding it as a landmark human rights advance to one of a disastrous anarchic profiteering sham. Most may agree, though, that the trillion-dollar war on weed has been a failed policy, a vehicle for the hideous expression of our racism, diverting law enforcement resources away from violent crime, and yet having no appreciable effect on marijuana availability. Yes, legalization might free up law enforcement, but opponents argue that legalization may increase marijuana use among the youth, not because they couldn't get it before, but because it'll be cheaper and more socially acceptable. In other words, the argument goes, think about the children. So what happened in states like Washington and Colorado after they legalized marijuana? Among teens in Washington state, perceived harmfulness indeed went down and marijuana use went up, doubling from 2 to 4 percent. In contrast, no change in Colorado, but presumably that's because they had five years of commercialized medical marijuana before recreational use became legal, and indeed with the original liberalization in Colorado, perceptions of risk among teens dropped more than elsewhere, and rates of dependence went up. A frequently cited concern with legalization is that it would allow the rise of big cannabis, similar to big tobacco and big alcohol. After the cannabis industry successfully beat back pesticide regulations in Colorado, public health advocates experienced a feeling of deja vu, trying to mitigate the adverse public health consequences in the face of an industry that just aims to maximize profit. The biggest concern, though, may not be big cannabis turning into big tobacco, but rather big tobacco turning into big cannabis. Marijuana legalization advocates may not have considered the potential effects of the multinational tobacco companies entering the market. Internal memos show that big tobacco have just been waiting in the wings for the right time to strike. The fact that they created perhaps the leading cause of preventable death in the world shows how much they care about people compared to profits, so that should raise some red flags. Big tobacco is expected to profit from legalization, whether or not it takes over, though, as frequent cannabis use is a predictor of future cigarette addiction. For teen non-smokers, weekly cannabis use predicted a more than eight-fold increase in the odds of moving from just joints to cigarettes. This may be because tobacco is commonly mixed with cannabis to help it burn more smoothly. Thus, cannabis use may indirectly expose one to tobacco, which may be seven or times more addictive than cannabis. Or it may just be that teens who smoke marijuana are hanging out more with a crowd that tends to smoke more cigarettes, and that's the reason, though even after controlling for pure use, cannabis does still seem to be a gateway drug to tobacco, and perhaps is a way to deal with cannabis withdrawal. Either way, one of the most potentially harmful effects of cannabis is that it may lead to nicotine addiction, which wipes out nearly five million lives every year, about 24 times more than all illegal drugs combine.