There appears to be a shift in the United States in favor of relaxing marijuana laws, a topic that has dipped in and out of the national conversation for decades. Public perceptions about pot have come a long way, from the dire warnings of "Reefer Madness" to growing acceptance of medical marijuana. 
Members of a crowd numbering tens of thousands smoke and listen to live music at the Denver 420 Rally on April 20, 2013. Annual festivals celebrating marijuana are held around the world on April 20, a counterculture holiday. 
A man smokes a joint during the official opening night of Club 64, a marijuana social club in Denver, on New Year's Eve 2012. Voters in Colorado and Washington state passed referendums to legalize recreational marijuana on November 6, 2012. 
People light up near the Space Needle in Seattle after the law legalizing the recreational use of marijuana went into effect in Washington on December 6, 2012. 
Nutrient products are placed on shelves in the weGrow marijuana cultivation supply store during its grand opening on March 30, 2012, in Washington, D.C. The store is a one-stop-shop for supplies and training to grow plants indoors, except for the actual marijuana plants or seeds. Legislation was enacted in 2010 authorizing the establishment of regulated medical marijuana dispensaries in the nation's capital. 
Marijuana activist Steve DeAngelo wears a "Yes on Prop 19" button as he speaks during a news conference in Oakland, California, on October 12, 2010, to bring attention to the state measure to legalize marijuana for recreational purposes in California. Voters rejected the proposal. 
Sonja Gibbins walks through her growing warehouse in Fort Collins, Colorado, on April 19, 2010. Since the state approved medical marijuana in 2000, Colorado has seen a boom in marijuana dispensaries, trade shows and related businesses. So far 20 states and the District of Columbia have made smoking marijuana for medical purposes legal. 
A patient prepares to smoke at home in Portland, Maine, on October 22, 2009, a decade after the state approved a medical marijuana referendum. 
Coffeeshop Blue Sky worker Jon Sarro, left, shows a customer different strains of medical marijuana on July 22, 2009, in Oakland, California. Voters in the city approved a measure during a vote-by-mail special election for a new tax on sales of medicinal marijuana at cannabis dispensaries. 
Medicinal marijuana patient Angel Raich wipes her eyes during a press conference on March 14, 2007, in Oakland, California. The 9th circuit U.S. Court of Appeals in San Francisco ruled that 41-year-old Raich, who used medicinal marijuana to curb pain from a brain tumor as well as other ailments, did not have the legal right to claim medical necessity to avoid the possibility of prosecution under federal drug laws. 
Different varieties of medical marijuana are seen at the Alternative Herbal Health Services cannabis dispensary in San Francisco on April 24, 2006. The Food and Drug Administration issued a controversial statement a week earlier rejecting the use of medical marijuana, declaring that there is no scientific evidence supporting use of the drug for medical treatment. 
People in New York gather for a pro-cannabis rally on May 4, 2002. That same day, almost 200 similar events took place around the world to advocate for marijuana legalization. It was dubbed the "Million Marijuana March." 
Dennis Peron takes notes during a phone interview while Gary Johnson lights up at the Proposition 215 headquarters in San Francisco on October 11, 1996. The ballot measure was approved when voters went to the polls in November, allowing medical marijuana in California. 
A television ad aired in 1996 by Republican presidential candidate Bob Dole's campaign included footage from a 1992 MTV interview of a laughing President Clinton saying he would inhale marijuana if given the chance to relive his college days. 
President George H. Bush holds up a copy of the National Drug Control Strategy during a meeting in the Oval Office on September 5, 1989. In a televised address to the nation, Bush asked Americans to join the war on drugs. 
Robert Randall smokes marijuana that was prescribed to treat his glaucoma in 1988. He became the first legal medical marijuana patient in modern America after winning a landmark case in 1976. 
First lady Nancy Reagan participates in a drug education class at Island Park Elementary School on Mercer Island, Washington, on February 14, 1984. She later recalled, "A little girl raised her hand and said, 'Mrs. Reagan, what do you do if somebody offers you drugs?' And I said, 'Well, you just say no.' And there it was born." She became known for her involvement in the "Just Say No" campaign. 
President Jimmy Carter, with his special assistant for health issues, Dr. Peter Bourne, beside him, talks to reporters at the White House about his drug abuse control message to Congress on August 2, 1977. Among other things, he called for the elimination of all federal criminal penalties for the possession of up to one ounce of marijuana. 
Panel members of the National Commission on Marijuana and Drug Abuse attend a hearing In Denver on January 10, 1972. From left, Dr. J. Thomas Ungerleider, psychiatrist; Michael R. Sonnenreich, commission executive director; Raymond P. Shafer, commission chairman; Mitchell Ware, Chicago attorney; Charles O. Galvin, Dallas law school dean. The commission's findings favored ending marijuana prohibition and adopting other methods to discourage use, but the Nixon administration refused to implement its recommendations. 
Protesters wade in the Reflecting Pool at the National Mall in Washington during the "Honor America Day Smoke-In" thrown by marijuana activists in response to the official "Honor America Day" rally organized by President Nixon supporters at the Lincoln Memorial on July 4, 1970. 
Marijuana reform was the Life magazine cover story in October 1969. The banner read: "At least 12 million Americans have now tried it. Are penalties too severe? Should it be legalized?" 
Police dogs trained to smell out hidden marijuana examine U.S. soldiers' luggage at the airport during the Vietnam War in 1969. Drug use was widespread during the war. 
People share a joint during a 1969 concert in Portland, Oregon. In 1973, Oregon became the first state to decriminalize cannabis. 
Marijuana use became more widespread in the 1960s, reflecting the rising counterculture movement. 
Research scientist Dr. Reese T. Jones, right, adjusts the electrodes monitoring a volunteer's brain response to sound during an experiment in 1969 that used a controlled dosage of marijuana. The tests were conducted at the Langley Porter Institute at the University of California, San Francisco. 
U.S. Customs agents track the nationwide marijuana market during Operation Intercept, an anti-drug measure announced by President Nixon in 1969. The initiative intended to keep Mexican marijuana from entering the United States. 
Members of the Grateful Dead talk with reporters from their home in San Francisco on October 5, 1967. The band was protesting being arrested for marijuana possession. 
A woman buys ready-rolled marijuana cigarettes from a dealer at her door circa 1955. 
Even after Congress cracked down on marijuana in 1937, farmers were encouraged to grow the crop for rope, sails and parachutes during World War II. The "Hemp for Victory" film was released in 1942 by the U.S. Department of Agriculture. 
Marijuana cigarettes are hidden in a book circa 1940. Congress passed the Marijuana Tax Act in 1937, effectively criminalizing the drug. 
A poster advertises the 1936 scare film "Reefer Madness," which described marijuana as a "violent narcotic" that first renders "sudden, violent, uncontrollable laughter" on its users before "dangerous hallucinations" and then "acts of shocking violence ... ending often in incurable insanity." 
Harry Anslinger was named commissioner of the Federal Bureau of Narcotics when it was established in 1930. While arguing for marijuana prohibition, he played on Americans' fear of crime and foreigners. He spun tales of people driven to insanity or murder after ingesting the drug and spoke of the 2 to 3 tons of grass being produced in Mexico. "This, the Mexicans make into cigarettes, which they sell at two for 25 cents, mostly to white high school students," Anslinger told Congress. 
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- David Nathan: Medical marijuana debate obscures the issue of legalizing recreational use
- In legalizing pot, he says, concerns of both sides of the issue need to be considered
- Nathan: Goals are to keep it out of the hands of minors, reduce harm to adults, get revenue
- Nathan: Opponents and supporters of legalization must listen to each other's concerns
Editor's note: David L. Nathan, a clinical associate professor at Robert Wood Johnson Medical School, was inducted as a Distinguished Fellow at the 2013 Annual Meeting of the American Psychiatric Association in San Francisco. He teaches and practices general adult psychiatry in Princeton, New Jersey.
(CNN) -- It's becoming a cliché: The tide is turning in the debate over cannabis. Sanjay Gupta, CNN's chief medical correspondent, publicly reversed his position and now supports medical cannabis. Republican Gov. Chris Christie just expanded New Jersey's medicinal marijuana laws. In the past month, New Hampshire and Illinois have become the 19th and 20th states to approve medical marijuana.
But the debate over medical marijuana obscures the more fundamental issue of our failed war on pot and the path to smart legalization.
I had an opportunity to explore the full range of perspectives in the marijuana debate at the recent 2013 Annual Meeting of the American Psychiatric Association. What I learned can be simply stated: Nationwide cannabis legalization is coming and smart regulation is the key to its success.
At the convention, held in San Francisco, I listened to and spoke with respected leaders of the opposition to cannabis legalization, who are mostly specialized in the treatment of substance use disorders.
The Bay Area is a proving ground for California's liberal medical marijuana laws. Amanda Reiman, policy manager for the California branch of the pro-legalization Drug Policy Alliance, took me on a tour of local cannabis dispensaries. And Oaksterdam University invited me to speak at their makeshift headquarters -- their previous location was closed after a DEA raid last year -- where classes are offered on all things cannabis.
The dispensaries are largely self-regulated, yet all facilities are immaculate, security is tight, and members of the staff are knowledgeable about the science of cannabis. Surely not all points of access are as well-run as these dispensaries, but they could be. And only with legalization and regulation can we expect that they would be.
Most legalization advocates and opponents share concerns about underage pot use, an opposition to incarcerating users, and a recognition that marijuana is less harmful to adults than alcohol.
Opinion: Americans agree, pot is no crime
Most agree public opinion has shifted in favor of cannabis legalization, although the two groups have strongly divergent feelings about the change. A minority of advocates call for America to "free the weed" with few restrictions, while opponents at the American Psychiatric Association fear that legalization would lead to "a nation of drunken stoners" after an anticipated rise in adolescent use of this and other drugs.
Gupta: I was wrong about marijuana 
Gupta: Weed not a gateway drug Gupta: I was wrong about marijuana The substance abuse treatment community has legitimate concerns, and recreational cannabis should not be legalized -- for minors.
If national polls are correct, and wisdom prevails, then America is rapidly moving toward legal cannabis for adults. We must stop arguing about the right of consenting adults to consume a relatively safe recreational drug, and discuss how -- rather than whether -- cannabis should be properly regulated by the federal government.
First, the four essential goals of marijuana regulation are: keeping cannabis out of the hands of minors; reducing harm to adult users; preventing collateral harm to the public and getting the maximum economic benefit from legalization.
Our approach to federal regulation should synthesize the perspectives of both advocates and opponents of legalization. We should look to research on laws controlling alcohol, tobacco and gambling. We can also learn from Colorado and Washington, which have developed regulations for recreational cannabis, and the 18 other states -- plus the District of Columbia -- that have legalized medical marijuana.
We can achieve the essential goals of regulation if we:
• Require proper labeling of cannabis products, including the quantities of key ingredients like THC and CBD.
• Test cannabis products for contaminants and label accuracy.
• Require government supervision of all facilities involved in the production, distribution and sale of cannabis.
• Limit advertising, sales and public consumption of cannabis products the way we do with alcohol and/or tobacco.
• Ban cannabis packaging and advertising that targets or attracts underage users.
• Require child-resistant packaging for edible cannabis products.
• Impose penalties on adults who enable minors to get marijuana.
• Allow adults to grow a small number of cannabis plants for personal use.
• Prosecute cannabis-impaired driving with field sobriety tests.
• Continue restrictions on cannabis use by professionals and laborers when scientific evidence indicates that such use risks public safety.
• Empower states and municipalities to restrict the cannabis trade within their borders.
• Fund education of adults about the use and abuse of cannabis.
• Fund preventive youth education about the dangers of underage cannabis use.
• Fund treatment of adults and minors with cannabis use disorders.
• Tax all aspects of the cannabis trade at the highest rate that the free market will bear, using a portion of the proceeds to fund regulation, education and treatment.
Just as responsible fishermen support the conservation of marine ecosystems, even marijuana enthusiasts can offer smart ideas for the successful legalization of cannabis.
The fiercest critics of pot legalization have legitimate concerns, particularly about pot's effects on developing brains of young people. Advocates and opponents need to come together for an open-minded discussion about the regulation of marijuana in the United States.
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The opinions expressed in this commentary are solely those of David Nathan.
