Medical marijuana's potential as an alternative to dangerous, addictive prescription painkillers is earning is a closer look in Washington.

Between the lines: Most states allow medical uses of marijuana, but Attorney General Jeff Sessions has taken a hardline stance on marijuana prosecution. That conflict has heightened Congress' attention to the issue, and lawmakers are increasingly on the states' side.

Why it matters: Advocates say medical marijuana has several uses — including, as an alternative to opioid painkillers.

One study published in Journal of the American Medical Association found that states with medical marijuana laws had lower opioid overdose death rates.

"Opioids are a big, popular topic in statehouses nowadays. It’s just not there at the federal level because... [the administration is] just not willing to acknowledge that cannabis can be part of health care," said Jeremy Unruh, director of regulatory affairs of PharmaCann, a medical marijuana company.

The catch: There are more barriers to medical marijuana than opioid painkillers, even though opioids are at the center of the country's more pressing public health crisis.

"To me, it’s illogical to say, ‘We’re perfectly OK with having opioids prescribed, highly addictive opioids, but not look at cannabinoids," said Sen. Thom Tillis. "It just doesn’t make sense to me from a scientific perspective.”

Where it stands: The tension between state laws permitting medical marijuana and federal law classifying it as an illegal narcotic came to a head when Sessions released a memo directing U.S. attorneys to enforce federal law.

Congress has been working on legislation that would protect state law.

House and Senate committees have both passed measures designed to stop federal officials from standing in the way of states implementing their own own laws — which has become routine.

Sens. Cory Gardner and Elizabeth Warren recently introduced a bill that would essentially make federal law respect states' marijuana laws.

"Certainly there’s been a lot of preliminary research that shows it can be an alternative. And that’s one of the areas I’d like to see more research focused," Gardner said.

The problem: Marijuana's federal status as an illegal drug makes research into its medical benefits difficult.