The federal government considers marijuana to have no medical value. But US Surgeon General Vivek Murthy on Wednesday said "marijuana can be helpful" for some medical conditions and symptoms. And it seems like this wasn't a slip-up: the US Department of Health and Human Services appears to be promoting the comments on Twitter.

"We have some preliminary data that for certain medical conditions ... marijuana can be helpful" - @Surgeon_General : http://t.co/Y3sfhwJ0DJ — HHS Media (@HHSMedia) February 5, 2015

This is a big deal. In the past, these types of positive comments about pot have been walked back by public officials. There's even a West Wing episode in which the surgeon general almost had to resign after suggesting pot should be decriminalized — likely based off a similar controversy during the Clinton administration.

But HHS is actually repromoting Murthy's comments — a sign of how views about medical marijuana are changing.

Under the federal scheduling system, the feds consider marijuana to have no medical value and a high potential for abuse, putting it in the same category as heroin and an even higher restriction than cocaine.

To find medical value for a controlled substance, a drug must have large-scale clinical trials to back it up — similar to what the Food and Drug Administration would expect from any other drug entering the market.

But the federal government's prohibition of marijuana is part of the reason large-scale clinical trials have been so hard to conduct. As a result of pot's schedule 1 status, the Drug Enforcement Administration limits the supply of marijuana for research. To obtain it for studies, researchers must get their studies approved by the Department of Health and Human Services, FDA, and DEA.

Given these restrictions, the American Academy of Pediatrics recently called on the federal government to reschedule marijuana to allow more research into its potential health effects for sick children.

Changing marijuana's status as a schedule 1 drug is a bit of a catch-22. There needs to be a certain level of scientific research proving marijuana has medical value, but federal restrictions make that difficult.

Watch: Ezra Klein's take on the subject