More than 30 states have medical marijuana programs — yet scientists are only allowed to use cannabis plants from one U.S. source for their research. That's set to change, as the federal government begins to add more growers to the mix. Drew Angerer/Getty Images hide caption
What appears to be a makeshift greenhouse is seen behind a home where killings occurred in Aguanga, Calif. Several people were found fatally shot at the illegal marijuana growing operation. Elliot Spagat/AP hide caption
Mayor Quinton Lucas talks to demonstrators during a rally in Kansas City, Mo., on June 5, to protest the death of George Floyd. Charlie Riedel/AP hide caption
Louisiana, like many other states where cannabis is legal, has designated the cannabis industry as essential. Above, marijuana plants grow under special lights at GB Sciences Louisiana, in Baton Rouge. Gerald Herbert/AP hide caption
In San Francisco, dispensaries were first left off city's list of "essential businesses." The city's Department of Health now says "cannabis is an essential medicine for many San Francisco residents." Patrick T. Fallon/Bloomberg via Getty Images hide caption
Los Angeles District Attorney Jackie Lacey announced she has asked a judge to wipe out and seal cannabis-related convictions dating back to 1956. It's the culmination of a partnership with the nonprofit group Code for America which used computer-based algorithms to identify eligible cases. Marcio Jose Sanchez/AP hide caption
A marijuana plant grows in California's Shasta-Trinity National Forest. This plant is part of an illegal growing operation by highly organized drug cartels that take advantage of the forests' thick canopy to help hide their operations. Eric Westervelt/NPR hide caption
Come Jan. 1 it will be legal to smoke recreational marijuana in Illinois. But housing authorities say it will remain prohibited in public housing. Susan Montoya Bryan/AP hide caption
Workers prune marijuana plants at a Clever Leaves greenhouse in Pesca, Colombia. The company employs over 450 people. Courtesy of Clever Leaves hide caption
University of Pittsburgh researchers developed a prototype device that can measure the amount of THC in a person's breath. Courtesy of the University of Pittsburgh hide caption
Marijuana use is risky for teens and pregnant women and can be habit-forming, says the U.S. surgeon general. Jane Khomi/Getty Images hide caption
U.S. officers found nearly four tons of marijuana in a shipment of peppers in San Diego. U.S. Customs and Border Protection hide caption
A Court of Appeals ruled that "the odor of marijuana coupled with possession of what is clearly less than ten grams ... does not grant officers probable cause" to search and arrest a person. Gerald Herbert/AP hide caption
Cannabidiol, or CBD, is a compound that can be extracted from marijuana or from hemp. It doesn't get people high because it doesn't contain THC, the psychoactive component of the cannabis plant. Getty Images hide caption