The most commonly used illicit drug is marijuana. Probably it is the most controversial of all recreational drugs, as there are few people actively organizing for the reform of cocaine or heroin laws, but many would like to see marijuana laws changed. The debate on just how the laws should change and how marijuana ought to fit within American society has been plagued with misinformation long before the substance was made illegal by the federal government in 1937. The history, myths, and facts about the drug are set out anew in _Understanding Marijuana: A New Look at the Scientific Evidence_ (Oxford University Press) by Mitch Earleywine. The book is extremely useful as a summary of the research that has been done on marijuana; there are twenty-five pages of references at the end to guide anyone who needs further information. Only a specialist will need the references. _Understanding Marijuana_ is a broad and fair summary.
There is an enormous amount of misinformation about the drug, and while those that favor use and legalization may have spread their share of misinformation, the history of marijuana in the twentieth century and entering this one is a history of one scare tactic after another wielded by government agencies and individuals who wish to suppress marijuana use. Earleywine's book spends one chapter after another summarizing the experiments and statistics to debunk the most common scare stories. Cannabis intoxication does not lead to hostility, violence, or a climbing murder rate. Marijuana is not a gateway drug. There is no amotivational syndrome from marijuana use. College students who use marijuana get the same sorts of grades as students who do not. Earleywine was taught in junior high that marijuana smokers would have Cyclops-like children, but the drug has not been linked to birth defects, nor to a definitive decrease in reproductive function. In fact, marijuana might help the relatively common problem of hypoactive sexual desire disorder, but as Earleywine wryly notes, "Despite this potential promise, studies of cannabis's impact on sexual drives have not been a high priority of most research funding agencies." The claim current in "public service" ads is that using marijuana somehow funds terrorists; this was perhaps too recent to be included here, or else simply too stupid.
This is a sensible book to show that "marijuana is neither completely harmless or tragically toxic," but that it has minimal detrimental effects especially compared to drugs that are currently legal. Not only has Earleywine summarized a lot of data here, he writes clearly and entertainingly, often with a sly joke as a gift to a reader swimming in a sea of data. For instance, he writes about interesting studies that show that marijuana users learn to smoke efficiently, gauging their lung capacity and the amount that can be held without coughing, so that they get more out of a joint than new users. "Many eventually learn to inhale and report more impact from the drug. Some never learn to inhale and subsequently run for public office."
