Story highlightsCNN's Dr. Sanjay Gupta says we should legalize medical marijuana nowHe says he knows how easy it is do nothing "because I did nothing for too long"

Dr. Sanjay Gupta puts medical marijuana under the microscope again with "Weed 3: The Marijuana Revolution" at 9 p.m. ET Sunday on CNN, followed by "High Profits" at 10 p.m., a CNN Original Series exploring the business of legal, recreational cannabis in Breckenridge, Colorado.


Dr. Sanjay Gupta puts medical marijuana under the microscope.

I see signs of a revolution everywhere.

I see it in the op-ed pages of the newspapers, and on the state ballots in nearly half the country. I see it in politicians who once preferred to play it safe with this explosive issue but are now willing to stake their political futures on it. I see the revolution in the eyes of sterling scientists, previously reluctant to dip a toe into this heavily stigmatized world, who are diving in head first. I see it in the new surgeon general who cites data showing just how helpful it can be.

I see a revolution in the attitudes of everyday Americans. For the first time a majority, 53%, favor its legalization, with 77% supporting it for medical purposes.

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Support for legalization has risen 11 points in the past few years alone. In 1969, the first time Pew asked the question about legalization, only 12% of the nation was in favor.

I see a revolution that is burning white hot among young people, but also shows up among the parents and grandparents in my kids' school. A police officer I met in Michigan is part of the revolution, as are the editors of the medical journal, Neurosurgery. I see it in the faces of good parents, uprooting their lives to get medicine for their children -- and in the children themselves, such as Charlotte, who went from having 300 seizures a week to just one or two a month. We know it won't consistently have such dramatic results (or any impact at all) in others, but what medicine does?

I see this medical marijuana revolution in surprising places.

Girl's seizures spur medical marijuana legislation in Georgia

Among my colleagues, my patients and my friends. I have even seen the revolution in my own family. A few years ago, when I told my mother I was investigating the topic for a documentary, I was met with a long pause.

"Marijuana...?" She whispered in a half questioning, half disapproving tone. She could barely even say the word and her response filled me with self-doubt. Even as a grown man, mom can still make my cheeks turn red and shatter my confidence with a single word. But just last week she suddenly stopped mid-conversation and said, "I am proud of you on the whole marijuana thing." I waited for the other shoe to drop, but it didn't. Instead, she added, "You probably helped a lot of people who were suffering."

History of marijuana in America 40 photosHistory of marijuana in America 40 photosPublic perceptions about pot have come a long way, from the dire warnings of "Reefer Madness" to growing acceptance of medical marijuana and the legalization of recreational use.Hide Caption 1 of 40History of marijuana in America 40 photosHarry 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.Hide Caption 2 of 40History of marijuana in America 40 photosA 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."Hide Caption 3 of 40History of marijuana in America 40 photosMarijuana cigarettes are hidden in a book circa 1940. Congress passed the Marijuana Tax Act in 1937, effectively criminalizing the drug.Hide Caption 4 of 40History of marijuana in America 40 photosEven 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.Hide Caption 5 of 40History of marijuana in America 40 photosA woman buys ready-rolled marijuana cigarettes from a dealer at her door circa 1955.Hide Caption 6 of 40History of marijuana in America 40 photosMembers 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.Hide Caption 7 of 40History of marijuana in America 40 photosU.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.Hide Caption 8 of 40History of marijuana in America 40 photosResearch 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.Hide Caption 9 of 40History of marijuana in America 40 photosMarijuana use became more widespread in the 1960s, reflecting the rising counterculture movement.Hide Caption 10 of 40History of marijuana in America 40 photosPeople share a joint during a 1969 concert in Portland, Oregon. In 1973, Oregon became the first state to decriminalize cannabis.Hide Caption 11 of 40History of marijuana in America 40 photosPolice 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.Hide Caption 12 of 40History of marijuana in America 40 photosMarijuana 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?"Hide Caption 13 of 40History of marijuana in America 40 photosProtesters 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.Hide Caption 14 of 40History of marijuana in America 40 photosPanel 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.Hide Caption 15 of 40History of marijuana in America 40 photosPresident 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.Hide Caption 16 of 40History of marijuana in America 40 photosFirst 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.Hide Caption 17 of 40History of marijuana in America 40 photosRobert 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.Hide Caption 18 of 40History of marijuana in America 40 photosPresident 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.Hide Caption 19 of 40History of marijuana in America 40 photosA 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.Hide Caption 20 of 40History of marijuana in America 40 photosDennis 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.Hide Caption 21 of 40History of marijuana in America 40 photosPeople 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."Hide Caption 22 of 40History of marijuana in America 40 photosDifferent 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.Hide Caption 23 of 40History of marijuana in America 40 photosMedicinal 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.Hide Caption 24 of 40History of marijuana in America 40 photosCoffeeshop 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.Hide Caption 25 of 40History of marijuana in America 40 photosA patient prepares to smoke at home in Portland, Maine, on October 22, 2009, a decade after the state approved a medical marijuana referendum.Hide Caption 26 of 40History of marijuana in America 40 photosSonja 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.Hide Caption 27 of 40History of marijuana in America 40 photosMarijuana 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.Hide Caption 28 of 40History of marijuana in America 40 photosNutrient 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.Hide Caption 29 of 40History of marijuana in America 40 photosPeople 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.Hide Caption 30 of 40History of marijuana in America 40 photosA 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.Hide Caption 31 of 40History of marijuana in America 40 photosMembers 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.Hide Caption 32 of 40History of marijuana in America 40 photosSean Azzariti, an Iraq war veteran and marijuana activist, becomes the first person to legally purchase recreational marijuana in Colorado on January 1, 2014. Colorado was the first state in the nation to allow retail pot shops. "It's huge," Azzariti said. "It hasn't even sunk in how big this is yet."Hide Caption 33 of 40History of marijuana in America 40 photosIn April, Maryland became the 18th state to decriminalize marijuana possession. Research published by the Pew Research Center in February showed 54% of Americans support legalization of marijuana.Hide Caption 34 of 40History of marijuana in America 40 photosMatt Figi's 7-year-old daughter Charlotte was once severely ill. But a special strain of medical marijuana known as Charlotte's Web, which was named after the girl early in her treatment, has significantly reduced her seizures. In July, Rep. Scott Perry, R-Pennsylvania, introduced a three-page bill that would amend the Controlled Substances Act -- the federal law that criminalizes marijuana -- to exempt plants like Charlotte's Web that have an extremely low percentage of THC, the chemical that makes users high.Hide Caption 35 of 40History of marijuana in America 40 photosOn July 27, the New York Times published "High Time: An Editorial Series on Marijuana Legalization," which called for the federal government to repeal its ban on marijuana.Hide Caption 36 of 40History of marijuana in America 40 photosAlaska Cannabis Club CEO Charlo Greene prepares to roll a joint at the medical marijuana dispensary in Anchorage, Alaska, on Friday, February 20. Several days later, Alaska became the third state in the nation to allow recreational marijuana.Hide Caption 37 of 40History of marijuana in America 40 photosA woman smokes pot at her home in Washington, D.C., on Thursday, February 26. It was the first day it was legal to possess marijuana for recreational purposes in the nation's capital. Democratic Mayor Muriel Bowser defied threats from Congress by implementing a voter-approved initiative, making the city the only place east of the Mississippi River where people can legally grow and share marijuana in private.Hide Caption 38 of 40History of marijuana in America 40 photosEmployees make last-minute preparations before the grand opening of The Cannabis Corner in North Bonneville, Washington, on Saturday, March 7. The pot shop is the first city-owned recreational marijuana store in the country.Hide Caption 39 of 40History of marijuana in America 40 photosGeorgia Rep. Allen Peake celebrates with Kristi Baggarly, holding her daughter Kimber, after the state Senate approved Peake's medical marijuana bill Tuesday, March 24, in Atlanta. The bill will legalize possession of cannabis oil for treatment of certain medical conditions, such as the seizures suffered by Baggarly's daughter Kendle.Hide Caption 40 of 4001 marijuana33 marijuana32 marijuana31 marijuana30 marijuana29 marijuana28 marijuana27 marijuana26 marijuana25 marijuana24 marijuana23 marijuana22 marijuana21 marijuana20 marijuana19 marijuana18 marijuana17 marijuana16 marijuana15 marijuana14 marijuana13 marijuana12 marijuana11 marijuana10 marijuana09 marijuana08 marijuana06 marijuana05 marijuana04 marijuana03 marijuana02 marijuanacolorado marijuana 010101 marijuana update RESTRICTED03 marijuana update RESTRICTED04 marijuana update01 alaska marijuana 022001 marijuana 031002 marijuana 0310 RESTRICTEDallen peake gaEXPAND GALLERY

I don't think we had ever had a conversation like that one. At that moment, I saw a revolution that can bring you to tears.

The word revolution, comes from the Latin revolutio, to "turn around."

I had my own turn around a couple of years ago, and at the time it was a lonely place to hold a supportive position on medical marijuana. Hardly any government officials would agree to sit down and be interviewed on the topic. Even patients I spoke to were reluctant to share their stories.

It can be tricky, I learned, to be on the right side of science but on the wrong side of ideology.

It can be tricky to be on the right side of science, but on the wrong side of ideology.

Dr. Sanjay Gupta

When we put the first "Weed" documentary on television in August 2013, I didn't know if anyone would watch our yearlong investigation. Even worse, I didn't even know if they would care.

Is weed legal in your state?

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Just two years later, in "Weed 3," we are eyewitnesses to a revolution in full swing. You will ride along with us for the dawn of the first federally approved clinical study on the use of marijuana for PTSD. You will meet patients such as Sean Kiernan, an accomplished investment banker, and Amelia Taylor, a stay-at-home mom.

They are the remarkable and surprising faces of this revolution -- smart, successful and suffering -- unwilling to accept the fact that commonly prescribed medications often used to treat PTSD can be worse than the underlying disorder itself. Sean Kiernan nearly died, trying to get better.

You will see what weed really does to your brain, in crystal clear images. This time around, you will hear from the heads of government agencies earnestly sharing their point of view, both Democratic and Republican senators, and even the President of the United States.

This is what a revolution looks like.

Your medical marijuana questions answered

When "Weed 2: Cannabis Madness" aired in March 2014, Boston researcher Rick Doblin believed the right people were watching. Just four days later, Doblin received a letter in the mail he had been waiting on for seven years that finally provided federal approval for his marijuana study. The federal farm where Doblin would have to obtain his marijuana is on the campus of Ole Miss in Oxford, Mississippi. In anticipation of a scientific revolution, the production of research-grade marijuana there has increased 30-fold in just the past year.

Make no mistake, we have plenty of evidence that the approval and support of the federal government can fast track a revolution at a faster pace than we have yet seen.

It was the National Institute of Allergy and Infectious Diseases that spearheaded the research into a cure for AIDS, as well as stopping the spread of West Nile Virus. They were also responsible for the awesome task of eradicating polio and smallpox. Other successful federally backed programs include the human genome project, the BRAIN initiative and the Precision Medicine Initiative. There are no shortage of examples where the federal government has been a guardian of our public health needs, and you could argue that medical marijuana would also qualify as a worthwhile investment.

10 diseases where medical marijuana could have impact

There is now promising research into the use of marijuana that could impact tens of thousands of children and adults, including treatment for cancer, epilepsy and Alzheimer's, to name a few. With regard to pain alone, marijuana could greatly reduce the demand for narcotics and simultaneously decrease the number of accidental painkiller overdoses, which are the greatest cause of preventable death in this country.

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As I sat across from Sens. Kirsten Gillibrand (D-New York) and Cory Booker (D-New Jersey), I knew something extraordinary was happening.

They were reciting the story of Charlotte Figi and countless other children. They were quoting back the data we had shared from our earlier investigations. They were extolling the potential virtues of the plant, and all of that was before the interview even started. There was an impatience about them, and they seemed in a hurry to make a large dent in marijuana reform.

They want marijuana to be rescheduled. They want it now.

They want doctors to be able to prescribe it at VA hospitals all over the country. They want it now.

They want research dollars freed up to study the plant. They want it now.

They want their fellow lawmakers at the state and national level to acknowledge what most of the world, including the citizens of the United States, have known for a long time: Marijuana is a medicine, that should be studied and treated like any other medicine.

And they want all of it now.

I spent much of our interview challenging them. I needed to remind them that people, long before me or them, have been trying to do many of these same things for 40 years, and had been rejected every time. I reminded them that politicians have a hard time winning elections on the issue of marijuana but less difficulty losing them. I challenged them every step of the way. "This time will be different," Booker confidently told me as he walked out of the room.

Is marijuana as safe as -- or safer than -- alcohol?

I know how easy it is do nothing because I did nothing for too long. Take a good look at the data, educate yourself and talk to the patients, who are often out of options and find their hope in the form of a simple plant.

Journalists shouldn't take a position. It makes sense. Objectivity is king. But, at some point, open questions do get answered. At some point, contentious issues do get resolved. At some point, common sense prevails.

So, here it is: We should legalize medical marijuana. We should do it nationally. And, we should do it now.

9 things to know about legal pot

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