President-elect Donald Trump and Alabama Senator Jeff Sessions. REUTERS/Mike Segar

Confirmation hearings for President-elect Donald Trump's Cabinet kicked off on Tuesday with Alabama Senator Jeff Sessions, Trump's pick to head up the Justice Department.

Sessions and Trump, however, seem to differ on a critical issue: the legalization of medical marijuana.

In an April hearing, the Alabama senator said that "good people don't smoke marijuana" and slammed President Obama for admitting to smoking the drug in high school. He also infamously joked that the Ku Klux Klan was "OK until I found out they smoked pot."

Though Trump's administration hasn't yet discussed a specific policy on medical cannabis, the president-elect has differed with Sessions on the issue in the past. He told Bill O'Reilly in an interview last year that he's "100%" in favor of medical marijuana, and has indicated that he'll take a typical Republican strategy by letting states lead the charge on legalization.

Trump's incoming spokesman, Sean Spicer, was pushed to address the issue on Fox's "Outnumbered" on Tuesday.

"You now see, finally, there is a majority of Americans in this country who believe marijuana should be legal," Lisa Kennedy, a host, asked Spicer. "I worry that this attorney general is opposed to that."

Spicer responded that the incoming administration is all about Trump.

The question came up during the hearing on Tuesday afternoon. Sen. Mike Lee (R-UT) asked Sessions about federal cannabis prohibition, to which Sessions responded that "it is not so much the attorney general's job to decide what laws are enforced," and said that Congress should pass a law to "change the rule."

Sessions also admitted that arresting and imprisoning cannabis offenders is a "problem of resources" for the federal government, after questioning from Patrick Leahy (D-VT).

Trump takes over January 20. Jose Luis Magana/AP

To some experts, cannabis legalization, both medical and recreational, has already hit a tipping point. Four states voted to legalize cannabis recreationally on Election Day, while four others voted to legalize some form of medical cannabis, joining a host of other states with cannabis laws already on the books. This means that almost a quarter of all Americans could have legal access to the plant in the near future.

But it will fall on Trump's incoming administration — and a Justice Department likely led by Sessions, who opposes legalizing marijuana — to actually implement these laws.

Sessions has come under fire from pro-legalization Republicans who represent states such as Colorado, where there's already a thriving market for cannabis.

"My advice is always to and has been to respect states’ rights and to look at what other states are doing and wait and see what’s going to happen," Cory Gardner, a Republican senator from Colorado, told Bloomberg. "So I look forward to having that conversation with him."

Two sitting Republican House representatives, Dana Rohrabacher (R-CA), and Thomas Massie (R-KY), are also creating a bipartisan Cannabis Caucus to focus on cannabis reform at the federal level.

Similar to Trump's stance on medical marijuana, Rohrabacher wants to make "the states’ rights issue" a focal point of the Cannabis Caucus's strategy, reports DecodeDC.