People in 29 states can legally use medical marijuana for a variety of problems, including the relief of pain, anxiety or stress. But what if they want to travel with it?
Secure airport areas beyond the Transportation Security Administration checkpoints are under federal control, and the federal government classifies marijuana as a Schedule 1 (most harmful) substance, even in states where it is legal for adults to consume it.
The laws conflict, but federal law trumps state law, making it illegal to fly with marijuana in carry-on or checked luggage. It is also illegal to transport marijuana across state lines, even if both states have legalized it.
Still, some passengers, especially on domestic flights, take the risk, because searching for marijuana is not on the TSA's to-do list.
The agency focuses "on terrorism and security threats to the aircraft and its passengers," a spokesman, Bruce Anderson, said. Airport screeners are looking for things that can take down an airplane, like guns or explosives, not marijuana, he said.
But if screeners do notice marijuana in someone's carry-on or checked luggage, Anderson said, they will call in local airport law enforcement officials to deal with it.
The musician Melissa Etheridge said she used medical marijuana for pain relief when she was being treated for breast cancer. She is now starting her own cannabis business, offering products like baked goods, tinctures and prerolled marijuana cigarettes aimed at people with pain from arthritis, sports injuries or other conditions.
She said she had carried marijuana in her checked luggage, but always attaches her doctor's recommendation to it. "Once the TSA left a note that they had inspected my luggage, and they left it right on top of my weed," she said.
The conflict between legal consumers of marijuana and federal laws is bound to worsen. Doctors' recommendations for the drug are increasing as new medicinal uses are discovered. And the number of states legalizing medical and recreational marijuana continues to rise. At the same time, Attorney General Jeff Sessions favors stricter anti-marijuana law enforcement nationwide.
Etheridge said she had become more cautious about flying with marijuana.
So far, though, said Anderson of the Transportation Security Administration, "our policy and procedures in this have not changed."
Of the 54 million passengers who went through Denver International Airport in 2015, the TSA stopped just 29 for possession of marijuana, an airport spokesman, Heath Montgomery, said. In those cases, as long as the amount was legal for personal possession in Colorado — 1 ounce of dried flower, for example — the local police simply asked the flier to dispose of it, either by throwing it in the trash or taking it home. All 29 complied, and no tickets were issued.
In 2016, the airport did not keep a record of those stopped with the substance. "The bottom line is, it's not an issue," Montgomery said.
Sales of medical and recreational marijuana are legal in Colorado, and more than $1 billion of marijuana was sold through dispensaries last year, said Matthew A. Karnes, founder of GreenWave Advisors, which analyzes the industry. The comparatively small number of TSA stops at the airport may mean that travelers have gotten the message that it is illegal to fly with marijuana and they leave it behind.
Or perhaps they just pack it and travel with it in a way that is subtle enough not to draw attention to it, said Lisa Smith of Seattle. She often travels through airports with marijuana and says many of her friends do as well.
Local airport authorities handle the situation differently in different states. In Florida, where medical marijuana is legal but recreational use is not, few are stopped for possession in the airport, but they do face penalties. Eleven of the approximately 2.8 million passengers who were screened by TSA at Jacksonville International Airport in 2016 were detained for possession of marijuana, said Michael D. Stewart, the airport's director of external affairs. All were arrested or given a notice to appear in court, he said.
TSA agents with dogs that are sniffing people in line by security checkpoints are looking for explosives, not marijuana. Dogs assisting Customs and Border Protection agents, however, are searching for illicit drugs along with other illegal substances, but only among passengers arriving in the United States on international flights.
"Some people like a glass of wine to relax when they travel," Smith said. "I prefer a little marijuana." It is hard to find in some states, she said, so "it's easier to bring my own." Medical and recreational marijuana are legal in Washington state.
Typically she takes loose marijuana in a plastic child-safe pill container. "Only once has a TSA agent pulled the container out of my purse," she said, "but that was because she was looking for a water bottle that had set off the scanner."
The agent put the marijuana back, Smith said. "I don't think she noticed what it was."
Smith said she also traveled sometimes with edible forms of marijuana. "I'll take a couple of cannabis-infused chocolates or mints and transfer them from their packaging to a container that isn't labeled as a cannabis product," she said.
Cy Scott, co-founder of Headset, a marijuana industry data analytics company in Seattle, said the proliferation of new forms of cannabis made it easier to take the substance on a flight.
"Along with cookies and chocolates, there are transdermal patches, sublingual drops, vape pens and topical ointments," he said.
There are 70,000 unique marijuana products sold in Washington state alone, he said, "so there are endless ways to carry marijuana in a nonobvious way."
Jaime Ruiz, chief of the Northern Border and Coastal Waters branch of the Department of Homeland Security, would not speculate on whether the odors in every processed marijuana product would be picked up by a detector dog working for Customs.
"But by experience, our canines have been able to detect odors in unthinkable places and have found marijuana concealed in airtight containers," he said.