Last month, a number of e-sports leagues announced plans to institute drug tests designed to clamp down on the use of performance-enhancing drugs (PEDs) during tournaments. One such league, ESL , has now announced more details of what isn't allowed under its new drug testing regime, including one substance that doesn't exactly come to mind when PEDs are discussed: marijuana.

ESL is using a list of prohibited substances provided by the World Anti-Doping Agency for its new test procedures. That list includes natural and synthetic cannabinoids in a set of drugs that are "prohibited in-competition," separate from those that are prohibited from all use at any time.

As such, ESL says in its announcement that "recreational use of [marijuana] outside (before) the event days will not be punished. Using it during the tournament—from the start of the first day until the end of the last day of competition—is strictly prohibited."

Starting with the upcoming ESL Cologne event on August 22, ESL will be conducting randomized saliva tests among all competitors throughout the tournament (previous plans for skin tests were determined to not be as good a fit for the event). Saliva tests generally only detect very recent marijuana use—up to 24 hours ago, according to some reports—so they shouldn't register any false positives for someone who last got stoned a few days before the competition.

The widely reported relaxing effects of a marijuana high might seem like the opposite of what is needed for a high-octane twitch gaming tournament, but there are anecdotal reports of widespread marijuana use at some events. "I’ve seen a number of players at national tournaments who came in ‘baked’ purely so they could play better," Australian World Cyber Games Tournament Director Alex Walker said in a 2011 interview. Maybe a quick hit is just what players needed to calm their nerves and smooth out their jittery mouse hand before a high-pressure match.

In any case, e-sports pros should be glad drug testing wasn't in effect in 2003, when caffeine was still listed as a banned stimulant on WADA's list (and there are some in the organization that want it banned once more). Under that regime, participation in e-sports tournaments would likely be literally decimated many times over.

Drugs obtained via a valid prescription can still be used during ESL events, but only with a letter from a physician disclosed before the tournament starts. That loophole makes us wonder if we'll see a new cottage industry of doctors offering easy Adderall prescriptions to e-sports pros who want an edge, much like the proverbial doctor who offers legal medical marijuana to anyone complaining of the sniffles.

Players found violating the new drug policy can be banned from ESL events for up to two years, but there will also be smaller penalties based on the specifics of the offense.

"Our main goal is and always will be to maintain the fair play spirit and the integrity of our competitions, and we’re confident that the anti-doping policy is an important improvement that will help us advance as a sport," ESL said in its announcement. "It is a small, but in our eyes essential and meaningful step forward for professional gamers across all games, ESL as an event organizer, and the e-sports industry as a whole."