Have weed, will travel? Not quite.

The relaxation of marijuana laws in more than two dozen states has resulted in overlapping — and occasionally conflicting — state and federal rules that air travellers may find perplexing.

Airports in Denver, Las Vegas and Reno, Nevada, don’t allow pot on the premises — but Los Angeles International, the world’s fifth-busiest airport, now allows customers aged 21 and over to bring marijuana, a policy change made to accord with California law on personal consumption of the drug. So do the two largest Pacific Northwest airports: Sea-Tac and Portland International, which follow state laws in Washington and Oregon, respectively. The law in Oregon even allows travellers to carry marijuana on flights within the state — even though airlines prohibit pot.

“It’s a tangled web, for sure,” said Dave Bannard, an attorney with Kaplan Kirsch & Rockwell LLP in Boston, who consults with airports on marijuana and other regulatory issues. “Airports are having to come to grips with this in a way that nobody expected a few years ago.”

Regardless of the airport, your personal pot isn’t allowed beyond the security checkpoint, a federal zone where marijuana of any amount — irrespective of a medical purpose — remains illegal. The U.S. government classifies marijuana a “Schedule 1” drug, along with heroin, LSD and ecstasy. Most U.S. airlines, which traverse federal airspace, also prohibit marijuana aboard their flights.

The Transportation Security Administration is at airports to combat terrorism, not to police drugs. When agents find some, either on a traveller or in checked luggage, they call the airport police to deal with it. In places that have legalized pot, officers typically ask the traveller to dispose of it, store it in a parked vehicle or call a friend to take it, airport representatives said.

Portland police have responded to 83 calls regarding travellers’ marijuana this year through Sept. 30, compared to 74 in 2017. Los Angeles airport police are also responding to an increased number of TSA calls arising from pot, due to the state law changes, said Officer Rob Pedregon, a police spokesman.

“We’ve actually seen more of an increase in the checked luggage from people who don’t really understand” the California law, Pedregon said. “They go into the dispensaries and they say, ‘Oh, give me five pounds to take home to Texas with me.’” Airport police file drug charges against such high flyers about once per month, he said.

In some cases, if the TSA doesn’t detect your stash, you may actually get through and onto a flight. “If you don’t get searched, it doesn’t mean you didn’t break the law, it just means you got away with something — it’s like bringing in Cuban cigars from Montreal,” Bannard said.

In Las Vegas, the county installed 20 “amnesty boxes” at four area airports and the McCarran Airport rental car center in February for those who may have forgotten to leave their weed. The boxes have a drawer-drop to keep anyone from reaching inside and are bolted into concrete. They were “used almost immediately,” according to Christine Crews, a spokeswoman for McCarran International Airport. Abandoned bud is destroyed by the county government.

Airport officials, for the most part, have bigger issues to deal with than marijuana. “The people who drink alcohol, a lot of times are aggressive, but if they come in stoned, they’re much more mellow,” said Brian Kulpin, a Reno airport spokesman. “A lot of times, they’re apologetic.” 

Denver has more trouble with people trying to bring water bottles through security lines than marijuana, airport spokeswoman Stacey Stegman said.

Earlier this month, Canada became only the second country to legalize recreational pot nationally. The change prompted both U.S. and Canadian governments to issue travel reminders about U.S. marijuana laws.

“If a traveller is found to be coming to the U.S. for reason related to the marijuana industry, they may be deemed inadmissible,” Customs and Border Protection said in a statement on Canada’s pot change. Those who work in the industry but are visiting the U.S. for a reason unrelated to their business “will generally be admissible to the U.S.” The agency leaves such decisions to the discretion of CBP officers, which could pose some tricky questions for travellers quizzed about their employment, lawyers note.

“I would say, as a general matter: Tell the truth, but answer questions like you’re in a deposition. Answer the question truthfully and narrowly,” said Stanley Jutkowitz, a Washington attorney who runs the cannabis practice at Seyfarth Shaw.

Travelling with marijuana, or working in the industry, could also be grounds for removal from the TSA’s PreCheck or other U.S. Trusted Traveler programs aimed at speeding a traveller’s return into the country.

The U.S. Trusted Traveler programs have eight-million members, including 5.6 million for the Global Entry program as of Aug. 31, according to Customs and Border Protection. The agency declined to reveal how many Trusted Traveler privileges it has revoked and denied overall in recent years. An Oct. 15 request for that data by Bloomberg News under the Freedom of Information Act remains pending.

“As marijuana remains an illegal drug in the U.S., the use of it or involvement in the industry could make a person ineligible for Trusted Traveler membership,” CBP spokeswoman Stephanie Malin said in an email. 

U.S. law enforcement has long grappled with how to approach marijuana. The Justice Department notified prosecutors in 2013 that medical and personal possession of marijuana didn’t merit bringing federal cases. In January, then-U.S. Attorney General Jeff Sessions rescinded that notice, known as the Cole Memo, and left the matter largely to local prosecutors’ discretion. In practice, the outcome largely depends on the quantity of marijuana and the jurisdiction in which it is detected. In many places, a gram or so probably won’t raise eyebrows. A large suitcase packed with weed is likely to launch a state or federal prosecution.

Ultimately, changes at the federal level will be required to resolve the mess of U.S. marijuana rules, lawyers said. The Strengthening the Tenth Amendment Through Entrusting States Act, known as the STATES Act, is currently pending in Congress. The bill would exempt people and companies in states that have legalized marijuana from federal prosecution of marijuana under the U.S. Controlled Substances Act, leaving pot enforcement to the states. In June, a dozen governors, including four Republicans, wrote to congressional leaders seeking their support for the bill, which has both House and Senate versions. “The STATES Act is not about whether marijuana should be legal or illegal; it is about respecting the authority of states to act, lead and respond to the evolving needs and attitudes of their citizens,” the governors wrote.

Until Congress acts, most travellers with unused marijuana will be forced to ditch their stashes before they check in for their flight. According to Bannard and representatives at several airports, there’s been one clear beneficiary of the abandoned pot: rental car employees.

Five major U.S. rental car chains did not respond to emails seeking comment.

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