At the moment, Leah Heise's soon-to-open dispensary in Baltimore is just an empty room. She hopes that by early next year, she will be selling medical marijuana to those in need.

But she is nervous that dream could end prematurely.

"And not that it could just change. It could come to a screeching halt and there is no recourse for that," she says.

"You're not going to get your money back out of this type of venture if the federal government decides to shut everyone down."

Heise is troubled by recent moves made by U.S. Attorney General Jeff Sessions.

"I have concerns that he is not impartial," she says. "I don't think that he is looking at this issue with an open mind."

Tyler Kennedy, right, smells a marijuana sample from Noah Siialata at CannaDaddy's Wellness Center marijuana dispensary in Portland, Ore., on April 20, 2017. (Don Ryan/Associated Press)

Sessions is staunchly against marijuana use in any form, recreational or medical, a position that leaves uncertainty for dispensary owners, patients, marijuana advocates and state officials across the U.S.

In 2016, when he was still a senator, Sessions told a Senate committee that marijuana is "dangerous" and it is not something that "good people" smoke.

Speaking about Colorado's move to legalize recreational cannabis, he said: "We need grown-ups in charge in Washington to say marijuana is not the kind of thing that ought to be legalized, it ought not to be minimized, that it's in fact a very real danger."

At the moment, his powers to crack down on medical marijuana are limited, but Sessions wants that to change.

Removing a legal barrier

Every year since 2014, Congress has included a clause in a spending bill that prevents the Department of Justice (DOJ) from interfering in medical marijuana programs in states where it is legal. Marijuana is allowed for medical use in 29 states, plus the District of Columbia.

Earlier this year, Sessions wrote to lawmakers asking them to scrap the provision, reminding them that according to the Drug Enforcement Administration (DEA), marijuana has no known medical benefits.

The Senate ignored his request, but a House committee followed through. A joint committee of the two could still include the provision in the spending bill before it expires in early December.

If the committee does not include the provision, David Mangone, a legislative analyst with Americans for Safe Access, a medical marijuana advocacy group, says patients should be concerned.

"The prohibition ... is the only thing that limits the [DOJ] from engaging in federal prosecution of patients ... that stops [it] from conducting large-scale raids or bringing federal penalties for a lot of these patients."

Marijuana products are displayed at a medical marijuana dispensary near Laytonville, Calif., on Oct.13, 2016. (Rich Pedroncelli/Associated Press)

A request for comment from Sessions on why he wants the provision removed was declined through his office.

Analysts believe ultimately Congress will keep the clause in the bill because it has broad partisan and public support.

But even if it does not, John Hudak, a senior fellow with the Brookings Institution, says he does not expect mass raids or prosecutions against dispensaries.

He points out Sessions has the power to go after recreational marijuana distributors in states like Washington or Colorado, but so far he has not.

There is another area, though, where Hudak says Sessions has been disruptive: researching the efficacy of marijuana as a medicine.

'At some point there is blood on his hands'

In the United States, marijuana is classified as a Schedule I drug by the DEA, the same as heroin and ecstasy, meaning it is considered to have a "high potential for abuse" and no "accepted medical use in treatment."

There is only one facility approved by the federal government to grow the plant for clinical research.

The DEA has received applications from about two dozen groups to grow and research marijuana, but so far the applications have been held up.

Speaking before a Senate committee last month, Sessions was vague about the status of the applications, saying only that one facility may not be enough, but two dozen are unnecessary.

Mangone argues marijuana should be researched to see what role it can play in alleviating the ongoing opioid crisis.

The Centers for Disease Control estimates more than 64,000 Americans died after overdosing on drugs last year. That is an average of 175 deaths a day.

Farmworkers remove stems and leaves from newly harvested marijuana plants at Los Suenos Farms in Avondale, Colo., on Oct. 4, 2016. (Brennan Linsley/Associated Press)

The American Legion has also called for marijuana to be reclassified and studied.

Since cannabis is still banned federally, Veterans Affairs doctors are prohibited by law from prescribing marijuana, even if it is legal in the state where they are treating patients.

Lou Celli, national director for veterans affairs with the Legion, says veterans "see this as a huge hypocrisy that the federal government will allow them to be issued opiates, but will not allow them to be issued a plant-based substance that can be far more effective in some cases, and far less toxic."

But Sessions has a different view, saying in March: "I am astonished to hear people suggest that we can solve our heroin crisis by legalizing marijuana so people can trade one life-wrecking dependency for another that's only slightly less awful."

Hudak disagrees with Sessions and says if marijuana can help alleviate the opioid crisis, "and the attorney general is actively preventing research into those questions, you have to consider at some point there is blood on his hands."

Keeping the status quo

Since the appointment of Sessions, states have wondered what will happen to their marijuana programs, both medical and recreational.

California was the first state to allow medical marijuana, back in 1996. In 2012, Washington and Colorado were the first to legalize recreational use.

Under the Obama administration, the DOJ issued guidelines in 2013 known as the "Cole Memo" saying it would not interfere with marijuana programs as long as states adhered to certain priorities, including keeping cannabis away from minors.

In April of this year, Sessions formed a task force to review the memo, but The Associated Press reports that documents it has obtained show it largely recommended staying with the current policy and not a crackdown on the industry.

Sessions's deputy, Rod Rosenstein, says the department is still reviewing the Cole Memo.

"I think there is some pretty significant evidence that marijuana turns out to be more harmful than a lot of people anticipated, and it's more difficult to regulate than I think was contemplated ideally by some of those states," he said in September.

Lead grower Dave Wilson cares for marijuana plants in the Flower Room at the Ataraxia medical marijuana cultivation centre in Albion, Ill., on Sept. 15, 2015. (Seth Perlman/Associated Press)

Sessions has also written to the governors of Washington, Oregon, Alaska and Colorado, four states where recreational marijuana is allowed, saying he has "serious concerns" about the effects of legalization.

Hudak predicts Sessions will alter the Cole Memo, although he isn't sure exactly how he will change the guidelines. But fears that Sessions will be able to shut down the entire industry are over-hyped, Hudak says.

He believes if there is enforcement, Sessions will go after easy targets: people who are not following the rules within the legal system.

"You are going to continue to see an attorney general who either keeps the status quo or does what he can to stand in the way of reform."

If Sessions does try to crack down on marijuana, he could run up against a formidable obstacle — his own boss: U.S. President Donald Trump.

On the campaign trail, Trump said he was for medical marijuana, adding the issue should be dealt with by individual states.

Since his election, though, Trump hasn't spoken much about the issue. That leaves many people confused, Hudak says, over who will win the debate on medical marijuana: Trump or his attorney general.