Those states include Ohio, which is in the process of working on regulations for its own medical marijuana legalization. Aaron Marshall, a spokesman for Ohioans for Medical Marijuana, said his hope remains with Trump, who has repeatedly said he supports leaving marijuana legalization efforts to the states.
"We're hopeful he'll follow the promises of President-elect Trump and leave it up to the states," Marshall said.
But Sen. Jeff Sessions, the Alabama Republican whom Trump has tapped to head the Justice Department, said as recently as April that "good people don't smoke marijuana," calling the drug "not the kind of thing that ought to be legalized."
He has referred to marijuana reform as a mistake and has been consistently critical of the Obama administration for refusing to enforce a federal prohibition on marijuana.
Tom Haren, a Cleveland-based lawyer who works on marijuana issues, calls Sessions "one of the most ardent prohibitionists, one of the most ardent drug warriors in the Senate." He sees a conflict between Sessions' words on the issue and Trump's.
"Trump is kind of a wild card himself on any number of issues," Haren said. "But he's been pretty consistent when it comes to medical marijuana that he supports it."
As a candidate for president, Trump in June 2015 seemed supportive of medical marijuana, but he called recreational adult use "bad" at a conservative CPAC conference. He expressed dismay at Colorado's recreational legalization, saying it has led to "some big problems."
"But I think medical marijuana, 100 percent," he said.
Haren said he sees a variety of scenarios that could play out in the new administration. The federal government could, he said, crack down on recreational markets and not on medical markets. It could, he said, regulate marijuana through the FDA, ultimately dispensing it at pharmacies. Or it could send "cease and desist" letters to some of the largest operators in the country, effectively overruling state efforts.
"I think the best-case scenario folks can hope for is to maintain the status quo," he said.
Haren said Sessions is not the only marijuana hard-liner in Trump's cabinet picks. Rep. Tom Price, the Health and Human Services pick, also "is a well-known prohibitionist."
But Sessions, Haren said, was picked for immigration. Price, R-Ga., was picked because of his opposition to Obamacare.
"My point is, I don't know that his selection is necessarily a signal from President-elect Trump's administration as to how this will affect legal marijuana," he said. He said Sessions' confirmation hearings might shed more light on his intentions.
In all, 28 states and three territories -- including the District of Columbia -- have legalized either recreational or medical marijuana. The first to support it for recreational purposes was Colorado, which did so in 2012. In response to that, the Department of Justice wrote a memo to all U.S. attorneys saying that in communities that enacted laws legalizing marijuana, "conduct in compliance with those laws and regulations is less likely to threaten the federal priorities." In essence: They wouldn't get involved.
But Carla Lowe, founder of Citizens Against Legalizing Marijuana, hopes that that policy ends in the new administration.
"We have great hope in Sen. Sessions," Lowe said. "He knows what marijuana is. He knows it's a highly potent and long-active addictive drug."
Lowe argues that medical marijuana is a "joke," aimed at luring people into thinking marijuana is acceptable. She has watched the spread of legalized marijuana with dismay.
"Federal law is our only hope," she said.
Robert Myatt, chairman of the Ohio chapter of Citizens Against Legal Marijuana, also said he thinks Sessions was chosen more for his stance on immigration than medical marijuana. "It's a side issue," for the administration, he said.
That said, "I would welcome an attorney general that would enforce federal drug laws," Myatt said.
He said he thinks if enforcement were to happen, it would affect recreational marijuana more than it would medical marijuana.
"It would be a terrible day for hundreds of thousands of Americans who are going to be helped by medical marijuana," said Marshall, of Ohioans for Medical Marijuana. "These are seriously ill patients who deserve the right to medicine that is going to work for them. We have an opioid crisis in Ohio and many other states, and medical marijuana is a far better choice for pain management than opioids."
Robert Capecchi, director of federal policies for the Marijuana Policy Project, said increased enforcement might be impractical, particularly with so many states having at least partially legalized the drug.
"It would be very costly, both in tax resources and manpower, to try to wipe these state laws off the books through federal enforcement," he said.
"You can't commandeer state law enforcement resources and force state law enforcement officers to enforce federal law," he said.
(c)2016 The Columbus Dispatch (Columbus, Ohio)
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