The UFC will no longer punish fighters for using marijuana, the promotion and the United States Anti-Doping Agency (USADA) have announced.
Previously, fighters were only tested for THC - marijuana's main psycho-active ingredient - in-competition, meaning a 10-day window either side of a scheduled bout.
Under the new rules, there will be no repercussions for fighters who test positive for marijuana unless "further evidence demonstrates the substance was taken for performance-enhancing purposes".
"While we want to continue to prevent athletes from competing under the influence of marijuana, we have learned that blood and/or urine levels of carboxy-THC have little-to-no scientific correlation to impairment," UFC senior vice president of athlete health and performance Jeff Novitzky says.
"THC is fat soluble, meaning that once ingested, it is stored in fatty tissues and organs in the body and can be released back into the blood or urine, sometimes long after ingestion."
Novitzky says athletes still won't be able to compete while under the influence of the drug, but USADA will employ visual and cognitive tests to make any determination in that area rather than blood level testing, which can often indicate usage well outside the competition window.
"The bottom line is that in regards to marijuana, we care about what an athlete consumed the day of a fight, not days or weeks before a fight, which has often been the case in our historic positive THC cases," Novitzky says.
The use of marijuana and CBD oils is widespread among the MMA fighting community, with many openly promoting products in states where the drug has been legalised, particularly California.
Kiwi UFC superstar Israel Adesanya has been open regarding his marijuana use, taking a stance against it criminalisation in New Zealand.
"Based on my informal discussion with athletes, there’s a significant number of percentage of athletes that choose to use marijuana, many for legitimate reasons outside of recreational," Novitzky notes.
"Many use it for pain control, anti-anxiety, to sleep, in lieu of more dangerous, more addictive drugs, so hopefully this being the first step to opening that up so that an athlete on Wednesday night of fight week instead of going to a Vicodin because their knee hurts and they can’t sleep can use a little bit of cannabis and get to sleep and have that pain control.
"It has no effect whatsoever on a competition on Saturday night, so it’s the right move, and I’m really excited about this revision and that specific policy change."