Doug Fine is the author of "Too High to Fail: Cannabis and the New Green Economic Revolution," in which he followed one legal medicinal cannabis plant from farm to patient.

By Doug Fine | Special to The Washington Post

With 16 states having decriminalized or legalized cannabis for non-medical use and eight more heading toward some kind of legalization, federal prohibition's days seem numbered. You might wonder what America will look like when marijuana is in the corner store and at the farmers market. In three years spent researching that question, I found some ideas about the plant that just don't hold up.

1. If pot is legal, more people will use it.

As drug policy undergoes big changes, I've been watching rates of youth cannabis use with interest. As it is for most fathers, the well-being of my family is the most important thing in my life. Whether you like the plant or not, as with alcohol, only adults should be allowed to partake of intoxicating substances. But youth cannabis use is near its highest level ever in the United States. When I spoke at a California high school recently and asked, "Who thinks cannabis is easier to obtain than alcohol?," nearly every hand shot up.

In Portugal, by contrast, youth rates fell from 2002 to 2006, after all drugs were legalized there in 2001. Similarly, a 2011 Brown University-led study of middle and high school students in Rhode Island found no increases in adolescent use after the state legalized medical marijuana in 2006.

As for adult use, the numbers are mixed. A 2011 University of California at Berkeley study, for example, showed a slight increase in adult use with de facto legalization in the Netherlands (though the rate was still lower than in the United States). Yet that study and one in 2009 found Dutch rates to be slightly lower than the European average. When the United States' 40-year-long war on marijuana ends, the country is not going to turn into a Cheech and Chong movie. It is, however, going to see the transfer of as much as 50 percent of cartel profits to the taxable economy.

2. Law enforcement officials oppose legalization.

It is true that many law enforcement lobby groups don't want to end America's most expensive war (which has cost $1 trillion and counting), but that's because they're the reason it's so expensive. In 2010, two-thirds of federal spending on the drug war, $10 billion, went toward law enforcement and interdiction.

But law enforcement rank and file know the truth about the drug war's profligate and ineffective spending, says former Los Angeles deputy police chief Stephen Downing, one of 5,000 public safety professionals who make up the group Law Enforcement Against Prohibition. "Most law enforcers find it difficult not to recognize the many harms caused by our current drug laws," he wrote to me in an e-mail. Those harms include, according to a new ACLU report, marijuana-possession arrests that are skewed heavily toward minorities.

Since marijuana prohibition drives the drug war, these huge costs would end when federal cannabis law changed. Sheriff Tom Allman in Mendocino County, Calif., helped permit, inspect and protect local cannabis farmers in 2010 and 2011. When I asked him why, he said: "This county has problems: domestic violence, meth, poverty. Marijuana isn't even in the top 10. I want it off the front pages so I can deal with the real issues."

3. Getting high would be the top revenue generator for the cannabis plant.

I called both of my U.S. senators' offices to support inserting a provision into this year's farm bill to legalize hemp for domestic cultivation. Based on my research on industrial cannabis, commonly called hemp, I'm staggered by the potential of this plant, which is not the variety you smoke.

In Canada, where 90 percent of the crop is bought by U.S. consumers, the government researches the best varieties for its hemp farmers, rather than refusing to issue them permits, as the United States tends to do. In a research facility in Manitoba, I saw a tractor whose body was made entirely of hemp fiber and binding. BMW and Dodge use hemp fibers in their door panels, and homes whose insulation and wall paneling are made partially of hemp represent a fast-growing trend in the European construction industry.

Jack Noel, who co-authored a 2012 industrial hemp task force report for the New Mexico Department of Agriculture, says that "within 10 years of the end of the war on drugs, we'll see a $50 billion domestic hemp industry." That's bigger than the $40 billion some economists predict smoked cannabis would bring in.

Foods such as cereal and salad dressing are the biggest U.S. markets for hemp today, but industrial cannabis has the brightest future in the energy sector, where a Kentucky utility is planning to grow hemp for biomass energy.

4. Big Tobacco and Big Alcohol would control the legal cannabis industry.

In 1978, the Carter administration changed alcohol regulations to allow for microbreweries. Today the craft-beer market is worth $10.2 billion annually. The top-shelf cannabis farmers in California's Emerald Triangle realize this potential. "We're creating an international brand, like champagne and Parmigiano cheese," says Tomas Balogh, co-founder of the Emerald Growers Association in Humboldt, Calif. Get ready for the bud and breakfast.

When America's 100 million cannabis aficionados (17 million regular partakers) are freed from dealers, some are going to pick up a six-pack of joints at the corner store before heading to a barbecue, and others are going to seek out organically grown heirloom strains for their vegetable dip.

As Balogh puts it: "When people ask me if the small farmer or the big corporation will benefit from the end of prohibition, I say, 'Both.' The cannabis industry is already decentralized and farmer-owned. It's up to consumers to keep it that way." So Big Alcohol might control the corner store, but not the fine-wine shop or the farmers' market.

5. In the heartland, legalization is a political nonstarter.

President Obama, in an interview last December, for the first time took seriously a question about the legalization of cannabis. He said that he didn't yet support it but that he had "bigger fish to fry" than harassing Colorado and Washington.

In Colorado in 2012, 40 percent of Republican voters chose to legalize cannabis, and a greater share of Coloradans voted for legalization than voted for Obama.

In Arizona, a pretty conservative and silver state, 56 percent of those in a poll last month supported regulating cannabis for personal use. Maybe fiscal conservatives know about the $35 billion in annual nationwide tax savings that ending prohibition would bring. In Illinois, 63 percent of voters support medicinal marijuana, and they're likely to get it. Even 60 percent of Kentuckians favor medical cannabis.

I'm not surprised. I live in a conservative valley in New Mexico. Yet as a woman in line at the post office recently told me: "It's pills that killed my cousin. Fightin' pot just keeps those dang cartels in business."