Medical marijuana caregiver Bret Kantola examines the bud on a new strain of medicinal marijuana that he is growing in his grow facility in Denver, on June 23, 2011. #

A worker trims cannabis at the growing facility of the Tikun Olam company near the northern city of Safed, Israel, on March 7, 2011. In conjunction with Israel's Health Ministry, Tikon Olam are currently distributing cannabis for medicinal purposes to over 1,800 people in Israel. #

A nurse helps a patient to inhale cannabis fumes from a vaporizer at the Hadarim nursing home in Kibutz Naan, Israel, on March 09, 2011. In conjunction with Israel's Health Ministry, The Tikon Olam company is currently distributing cannabis for medicinal purposes to over 1,800 people in Israel. #

Riot Special Forces policemen load a helicopter with six tons of marijuana found in a bunker during a raid in the Morro do Alemao shantytown on November 28, 2010 in Rio de Janeiro, Brazil. #

A cat stands near packs of confiscated marijuana in Cali, Colombia, on February 15, 2012. Colombian narcotics police seized 3.6 tons of marijuana from drug trafficking gangs in a food truck in Tulua Valle, according to the authorities. #

A soldier guards a detainee during a presentation for the media in Tijuana, Mexico, on October 18, 2010. On a conjoined operation with the army, local and state police seized 105 tons of U.S.-bound marijuana, and eleven suspects were detained. #

Travel guide Rick Steves speaks during a news conference announcing the filing of an initiative to legalize possession of marijuana in Washington state, on June 22, 2011, in Seattle. New Approach Washington, a coalition group including Steves, Seattle City Attorney Peter Holmes, former U.S. Attorney John McKay and the state ACLU chapter, is pushing an initiative to the Legislature that would regulate the recreational use of marijuana in a way similar to how the state regulates alcohol. #

A man who identified himself as a medical marijuana patient poses with a new billboard erected on top of a liquor store in Denver April 6, 2012. Colorado voters will decide in November whether to legalize marijuana for recreational use, regulating it like alcohol products. #

The rifle of a federal agent is seen through a marijuana leaf during the destruction of a marijuana plantation on the outskirts of the town of Casas Grandes, in the Mexican state of Chihuahua, on July 18, 2011. Federal agents located and destroyed 9 marijuana plantations totaling 7.4 acres, local media reported. The federal forces incinerated nearly 10 tons of the drug and no detentions were reported. #

A marijuana themed belt adorns the victim of an apparent drug-related execution on February 29, 2012 in Acapulco, Mexico. Drug violence surged in the coastal resort last year, making Acapulco the second most deadly city in Mexico after Juarez. One of Mexico's top tourist destinations, Acapulco has also suffered a drop in business, especially from foreign tourists, due to drug violence in the last year. Tourism accounts for some 9 percent of Mexico's economy and about 70 percent of the output of Acapulco's state of Guerrero. #

A soldier throws diesel fuel onto marijuana blocks before setting them on fire in Tijuana, Mexico, on January 28, 2011. According to the army, nine tons of marijuana among another drugs seized during several operations were destroyed. #

Oaksterdam University founder and veteran medical marijuana activist Richard Lee poses for a portrait before a news conference at the school in Oakland, California, on April 18, 2012. Lee announced his resignation as president of the school, referred to as the "Princeton of Pot," after federal agents recently shut down the school in a raid. #

A man smokes marijuana from a vaporizer during the 24th annual High Times Cannabis Cup in Amsterdam, Netherlands, on November 20, 2011. People who buy a judge's pass for the festival can vote in the annual competition electing the best marijuana and awarding it with the Cannabis Cup. The Netherlands, long-time known for its liberal drug policies, is changing course as right-wing political leaders are trying to ban tourists from buying marijuana in coffee shops. #

Britt Freitas holds up her new medical cannabis patient identification card at the Patient ID Center in Oakland, California, on March 22, 2012. California has seven times as many residents as Colorado, but nearly nine times fewer medical marijuana users, at least on paper. And as far as record-keepers know, the most populous state, home to the nation's first and most liberal medical marijuana laws, also has a smaller number of pot patients than Arizona, Hawaii, Michigan, Montana and Oregon. #

A patient is served at a medical marijuana center in Denver, Colorado, on April 2, 2012. With Colorado voters set in November to decide whether to defy the federal government and legalize marijuana for recreational use under state law, the enforcement division could play a key role in bringing a black market pot trade out of the shadows. #

Medical marijuana grower James Anderson looks glumly over the remains of a Golod Hill, Oregon garden that held hundreds of pot plants before federal agents pulled them out and hauled them away on September 29, 2011. Anderson said he and others growing on the property were within the limits of the Oregon Medical Marijuana Plan, but that U.S. Drug Enforcement Agency took them anyway. #

This December 13, 2011 photo released by the Oregon State Police shows the interior of a car driven by two men arrested Monday night after leading Oregon State Trooper Clay Core on a 100 mph chase along Interstate 5 south of Eugene, Oregon, while ripping open half-pound bags and flinging marijuana buds out the window. Troopers and deputies recovered approximately 5 pounds of marijuana along the roadway and from the car. Core says that the pot was "pelting my car" as the chase continued. #

An aerial view shows parts of the biggest marijuana plantation ever found in Mexico, in San Quintin, about 350 km (220 mi) away from Tijuana, on July 13, 2011. Mexican soldiers discovered the plantation in a remote desert, a top army officer said on Thursday. Soldiers patrolling the area found 300 acres (120 hectares) of pot plants being tended by dozens of men. #

An aerial view of marijuana plants growing in the backyard of a home in Fresno, California, on October 12, 2011. California narcotics officers have pulled millions fewer pot plants from remote forests than in past years because they claim drug traffickers have come down out of the mountains to plant pot in backyards and on prime farmland. #

Employee Stephen Young restocks the shelves behind bullet-proof glass at Northwest Patient Resource Center in Seattle, Washington, on January 27, 2012. Supporters of legalizing marijuana for recreational use have submitted enough signatures to put the matter to voters in Washington state in a bold move that, if successful, could put the state on a collision course with the federal government. #

Angeline Chilton a suburban Denver woman with multiple sclerosis who smokes pot twice a day to ease tremors, holds her pipe as she sits on the front porch of her home in Lakewood, Colorado, on March 6, 2012. Chilton insists that she never drives high, but she fears that officials will rush to set an unproven blood-level standard that would put her at risk of breaking the law. In Colorado and Washington, the debate over how to tell whether a driver is high is more than academic. The states are struggling to come up with a blood-level standard for marijuana that would be analogous to the blood-alcohol standard used to decide who's driving drunk. #

A 14-year-old Australian boy, accompanied by his translator, sits in front of the judge during his trial in Denpasar court, Bali, on November 25, 2011. An Indonesian court sentenced the Australian teenager from near Newcastle, New South Wales to two months in jail for possessing 3.7 grams of marijuana. #

U.S. border police in far-west Arizona seized a homemade off-road go-kart and trailer packed with marijuana, in the latest bizarre attempt by Mexican smugglers to beat beefed up border security. The Border Patrol's Yuma sector said agents and officers from the Cocopah Tribal Police Department spotted the single-seater go-kart hauling a trailer through the desert near Yuma, Arizona on Tuesday night and gave chase. The driver abandoned the vehicle, which was spray-painted a desert beige, fitted with knobbly off-road tires, and towing a trailer packed with 217 pounds of marijuana, about 100 yards from the border, and fled back to Mexico. #

A Mexican Army soldier stand guard inside a clandestine tunnel connecting warehouses on either side of California's border with Mexico in Tijuana, on November 4, 2010. Federal authorities in San Diego made one of the largest marijuana seizures in the United States, confiscating more than 20 tons of pot that was smuggled to the country through the underground tunnel that had lighting, ventilation and a rail system to send loads of illegal drugs into California. Mexican authorities also seized more than four tons of drug from the warehouse on their side. #

Packages containing marijuana are shown during a presentation to the media in Tijuana, on November 16, 2011. Police discovered a "major cross-border drug tunnel" running to California from Mexico, and seized 14 tons of marijuana, authorities said. #

A suspected drug dealer (right) is detained by a police officer from the National Directorate of Drug Control (DNCD) as he inspects his house in Santo Domingo March 10, 2012. Police, acting on information about illegal drug possession and sales from the residence, confiscated approximately 20 grams (0.7 ounces) of cocaine and 50 small packets of marijuana during the raid which ended in the arrest of seven people, all of whom will be processed by a tribunal, police said. #

A man holds a guitar with a sign which reads, "Smoking marijuana does not make me a delinquent", during a demonstration calling for the legalization of marijuana in Guatemala City, on March 23, 2012. #

Jerry Henry, 77, who uses medical marijuana for pain control, enters the Magnolia Wellness medical marijuana dispensary on its final day of business, in Orangevale, California, on December 16, 2011. As a going away present the alternative care dispensary gave each customer a free gram of high-quality pot. Magnolia Wellness was among dozens of dispensaries that closed since California's four U.S. attorneys announced that they were cracking down on marijuana cultivation and retail sales. #

People share a joint during a demonstration organized by the CIRC (research and information center) entitled "L'appel du 18 juin" (the call of June 18) to call for the legalization of the use of marijuana and hashish at the Parc de la Villette in Paris, France, on June 18, 2011. #