Marijuana Legalization: What Everyone Needs to Know, by Jonathan P. Caulkins, Angela Hawken, Beau Kilmer, and Mark A.R. Kleiman, Oxford University Press, 266 pages, $16.95 paper

Smoke Signals: A Social History of Marijuana—Medical, Recreational, and Scientific, by Martin A. Lee, Scribner, 519 pages, $35

In November, voters in Colorado and Washington approved groundbreaking ballot initiatives legalizing marijuana for recreational use. The measures immediately eliminated penalties for possessing up to an ounce and required state regulators to adopt rules for commercial production and sale by next July in Colorado and next December in Washington. Meanwhile, recent national surveys put support for legalization at 50 percent or more—the highest numbers ever recorded.

In this context of unprecedented public receptiveness to repealing cannabis prohibition, four centrist drug policy specialists—Jonathan Caulkins of Carnegie Mellon, Angela Hawken of Pepperdine, Beau Kilmer of the RAND Corporation, and Mark Kleiman of UCLA—have published Marijuana Legalization, a handy little paperback that aims to tell us "What Everyone Needs to Know" about the subject. Assiduously dedicated to a utilitarian, just-the-facts approach, Caulkins and his co-authors consider marijuana's benefits as well as its hazards, the harm caused by prohibition as well as the harm it prevents, the impact that legalization is apt to have not only on pot smoking but also on drinking, and the fiscal advantages, in terms of new tax revenue and lower law enforcement costs, of treating marijuana more like alcohol.

Along the way, they offer calm and generally fair-minded excursions into controversies such as the perils of increasing pot potency, the alleged link between cannabis and schizophrenia, and the extent to which marijuana prohibition enriches Mexican drug cartels. But after all this judicious weighing of costs and benefits, the authors conclude that the question of whether to legalize marijuana hinges on how you feel about getting high.

"In the end," Caulkins et al. write, "all the fancy benefit-cost analysis boils down to a rather simple proposition.…If you think marijuana intoxication is, on average, a good thing—counting both the happy controlled users and the unhappy dependent users—then a benefit-cost analysis done in a way that reflects your values will probably conclude that legalization improves social welfare. If you think marijuana intoxication is, on average, a bad thing, then an analysis that reflects your values will probably conclude that legalization harms social welfare—because the dominant outcome of legalization will be more marijuana use."

Although Caulkins and his colleagues do not put it this way, the implication is that the war on marijuana, ostensibly aimed at promoting public health and safety, is fundamentally a matter of taste. It is not even a moral crusade, strictly speaking, since there is no moral principle underlying the arbitrary legal distinction between marijuana and alcohol, which Hawken, in a separate essay toward the end of the book, concedes "makes no sense." As Martin Lee shows in Smoke Signals, his engaging and illuminating new history, marijuana's contraband status is a result of historical accident, racial prejudice, xenophobia, loads of cultural baggage, and an astonishing amount of ignorance. In this light, the coolheaded analysis offered by Caulkins et al. seems almost comical, since it presupposes that marijuana was banned for rational reasons.

While there is no shortage of books about marijuana, Lee, co-author of the fine LSD history Acid Dreams, brings new breadth and depth to the subject. His rich, wide-ranging account is a little skimpy in its coverage of recent developments but full of fascinating details from further back, including ancient medical uses of cannabis, the West's belated discovery of the plant's benefits, and its popularity within pre-hippie bohemian circles such as the 19th-century Club des Haschischins, jazz musicians of the 1920s and '30s, and Beat writers in the '40s and '50s.

Although cannabis has been consumed for thousands of years in India and China, Americans associated it with Mexico when they first became aware of it as a smoked intoxicant (as opposed to an ingredient in orally consumed patent medicines). Lee explains that Mexican peasants began smoking cannabis, possibly descended from hemp cultivated for fiber by Spanish colonists, in the early 1800s. Its use by Pancho Villa's revolutionary soldiers is memorialized in the folk song "La Cucaracha"—hence the term roach, "modern-day slang for the butt of a marijuana cigarette."

Marijuana's association with blacks and Mexicans, which marked it as an exotic drug used by inferior but scary outsiders, proved crucial to its prohibition. The bans began at the state level in 1915, when California outlawed the plant, and culminated in the federal Marihuana Tax Act of 1937. With marijuana as with opium, Lee observes, "the target of the prohibition was not the drug so much as those associated with its use."

Federal Bureau of Narcotics Commissioner Harry Anslinger warned that "marihuana causes white women to seek sexual relations with Negroes" and claimed that half the violent crimes in areas occupied by "Mexicans, Greeks, Turks, Filipinos, Spaniards, Latin Americans, and Negroes may be traced to the use of marihuana." Anslinger, who collected and circulated accounts of bloody crimes allegedly caused by marijuana, portrayed it as "the most violence-causing drug in the history of mankind" (a title that has since been seized by a succession of other drugs, often based on equally dubious evidence).

The notion that marijuana turns people into homicidal maniacs—which, Lee notes, was later replaced by the contradictory claim that marijuana turns people into passive, unmotivated layabouts—would have struck people familiar with the drug as patently absurd. But those people were not writing drug legislation. "Few members of Congress knew anything about cannabis when they voted to outlaw the herb," Lee notes. "'What is this bill about?' a congressman asked House Majority Leader Sam Rayburn from Texas, who replied, 'It has something to do with a thing called marihuana. I think it is a narcotic of some kind.'"

Marijuana's beyond-the-pale status was cemented when self-conscious dissidents (the Beats and then the hippies) embraced it, attracted largely by its illegality. Marijuana prohibition became self-perpetuating: The sort of people who were eager to use it as a signal of rebellion disgusted the sort of people who were determined to keep it illegal, and the plant's countercultural connotations have helped keep it illegal ever since.

"The serrated marijuana leaf had become a totem of rebellion, a multivalent symbol of societal conflict," Lee writes. "Condemning cannabis was a way to denounce the social and political movements that were in open revolt against 'the American way of life.'" While Lee gives a respectful hearing to Allen Ginsberg's view that "marijuana consciousness" is inherently subversive, he is appropriately skeptical of the notion that cannabis itself promotes a particular worldview, citing the old hippie saw that the drug might stop working if it were legalized.

Lee is much more excited about marijuana's medical potential. Perhaps a little too excited: His excursions into cannabinoid pharmacology and biology may tax the general reader's patience. Still, Lee is right to emphasize the importance of the medical marijuana movement, which is where most of the action in cannabis-related legal reform has been in recent years, especially when it comes to testing the boundaries between state and federal power.

One of the few disappointments in Lee's book is his discussion of Gonzales v. Raich, the 2005 case in which the Supreme Court ruled that the federal government's power to regulate interstate commerce extends even to homegrown marijuana used by patients in states that recognize the plant as a medicine. "Federal drug laws are rooted in the Commerce Clause, which empowers Congress to regulate interstate commerce," he writes. "This provision once served as an important tool for promoting progressive federal policies from the New Deal to Civil Rights, but over the years it became an all-purpose excuse for Congress to meddle in virtually every aspect of human behavior."

Contrary to what Lee seems to think, he is not describing two different legal trends. The Commerce Clause "became an all-purpose excuse for Congress to meddle in virtually every aspect of human behavior" because it "served as an important tool for promoting progressive federal policies from the New Deal to Civil Rights." If the Commerce Clause authorizes the federal government to punish a farmer for growing too much wheat, even when the extra grain never leaves his farm (as the Supreme Court held in the New Deal case Wickard v. Filburn), it is not much of a stretch to argue that the Commerce Clause also authorizes the federal government to punish patients for growing marijuana, even when the crop never leaves the state. If, as the Civil Rights Act of 1964 asserted, Congress can regulate any restaurant, cafeteria, lunchroom, lunch counter, or soda fountain when "its operations affect commerce" (e.g., when an Alabama diner uses Idaho potatoes to make French fries), surely the feds can shut down medical marijuana dispensaries, even when their activities are purely local and authorized by state law.

Notwithstanding the Supreme Court's absurdly broad reading of the Commerce Clause, states have room to experiment with new approaches to cannabis (and other drugs). As Caulkins et al. note, "The Constitution does not allow the federal government either to order state governments to create any particular criminal law or to require state and local police to enforce federal criminal laws." That's why opponents of Proposition 19, the California legalization initiative that lost by five percentage points in 2010, were wrong when they argued that the Supremacy Clause, which declares legitimate acts of Congress "the supreme law of the land," made the measure unconstitutional.

Even under national alcohol prohibition, which unlike the federal ban on marijuana was authorized by a constitutional amendment, states were free to go their own way. They could decline to pass their own versions of the Volstead Act (as Maryland did), repeal them (as a dozen states, including Colorado and Washington, did while the 18th Amendment was still in force), or simply refrain from prosecuting people under them (which was common in the wetter districts of the country). "The question is not whether a state could change its own laws," Caulkins et al. write. "Rather, the question is how the conflict with the continued federal prohibition would play out."

While the feds certainly can make trouble for any state that dares to legalize pot, there is a practical limit to what they can accomplish on their own. According to the FBI, there were 758,000 marijuana arrests nationwide in 2011, the vast majority for possession. State and local police departments were responsible for 99 percent of those arrests. It simply is not feasible for the Drug Enforcement Administration (DEA)—which has about 5,500 special agents nationwide, compared to about 765,000 sworn personnel employed by state and local law enforcement agencies—to bust a significant percentage of people who grow pot for themselves and their friends (as Colorado's law allows), let alone people who possess it for recreational use.

The DEA can raid state-legal pot shops, as it has done with medical marijuana dispensaries, but the number of potential targets will be considerably larger once the market officially expands to include recreational users. The Justice Department can use asset forfeiture as an intimidation tactic against landlords and threaten banks that accept deposits from pot businesses with money laundering charges. The Internal Revenue Service can make life difficult for pot sellers by disallowing their business expenses (but not, thanks to a tax law wrinkle, their "cost of goods sold," which includes the cost of buying marijuana). The feds could even threaten state regulators with prosecution for facilitating the trade, although that seems less likely, since it would provoke a direct confrontation with state officials. The one thing federal drug warriors cannot do, judging from their track record even when they have the full cooperation of state and local law enforcement agencies, is suppress the business entirely.

The ineffectiveness of prohibition is only part of the story, however, and it is not the most morally salient part. Lee highlights the basic injustice of using force to prevent people from smoking a politically incorrect plant, telling the stories of jazzmen hounded by Anslinger because of their deviant recreational preferences, activists targeted because of their conspicuous advocacy, medical users given outrageously long prison sentences, and people treated like drug kingpins because they grew pot for patients. "There is no moral justification for a policy that criminalizes people for trying to relieve their suffering," Lee writes. "Reefer madness has nothing to do with smoking marijuana—for therapy or fun or any other reason—and everything to do with how the U.S. government has stigmatized, prosecuted, and jailed users of this much maligned and much venerated plant."

Caulkins and his co-authors, by contrast, explicitly defend the proposition that forcibly protecting you from your own mistakes is a legitimate function of government, that it is not only possible to "make someone better off by coercing behavioral change" but desirable to do so, provided it can be done at an acceptable cost. Even if you buy that premise, shouldn't the distribution of these costs and benefits matter? For the most part, the people who are better off because prohibition stopped them from developing a life-disrupting addiction to pot are not the people who bear the burdens of this policy. Under prohibition, some are punished so that others may benefit.

"Tens of thousands of marijuana distributors are in prison," Caulkins et al. write, and "hundreds of thousands of people are arrested and convicted of marijuana violations each year. Quite apart from the budgetary costs to enforcement agencies, there is a real, though hard-to-quantify, cost to those individuals' welfare, in terms of direct suffering, reduced job prospects, and other effects." No kidding. But where Caulkins et al. see a cost that must be weighed (even though it can't really be measured), Lee sees a moral scandal built on a mountain of lies.

The two books nevertheless converge on something like a practical consensus. In four separate essays at the end of their book, Caulkins and his colleagues suggest a range of more tolerant approaches to cannabis, including "decriminalization plus home growing and sharing" (Caulkins), "permission for production and use through small not-for-profit cooperatives" (Kleiman), and experimenting with various forms of legalization (Hawken and Kilmer). "As a first step," Hawken says, "the federal government should step aside and let the states determine their own fate." We will soon discover how realistic that expectation is.