For baseball players taking advantage of a new drug policy in which marijuana use is permissible, the commissioner has a warning: Just don't show up to the ballpark high.

Even though Major League Baseball removed marijuana from its banned-substance list during the offseason, the league last week told teams that players remain subject to potential discipline for using or possessing the drug, according a memo obtained by ESPN.

In the memo, deputy commissioner Dan Halem wrote that the league maintains the right to punish players who break existing marijuana laws, such as possession and distribution, as well as for driving under the influence.

Players and team personnel who "appear under the influence of marijuana or any other cannabinoid during any of the Club's games, practices, workouts, meetings or otherwise during the course and within the scope of their employment" will undergo a "mandatory evaluation" for a potential treatment program, according to the memo.

While the penalty for a major league player testing positive for marijuana in the past was a fine, the biggest change addresses minor league players, for whom marijuana was a banned substance with a harsh suspension for testing positive. Minor league players rejoiced at the new drug agreement, in which MLB abandoned its marijuana policy for stricter testing on opioids.

Recreational marijuana is legal in cities inhabited by 12 major league teams: the A's, Angels, Blue Jays, Cubs, Dodgers, Giants, Mariners, Padres, Red Sox, Rockies, Tigers and White Sox. Medicinal marijuana is legal in 26 of 30 major league locations, with Georgia, Texas and Wisconsin the exceptions.

The minor leagues are far more restrictive in terms of location. More than 60 minor league cities are in states where both recreational and medicinal marijuana are illegal.

Despite the relative open-mindedness of MLB -- it has a particularly liberal policy, particularly when compared to the NFL, which only now is considering abolishing suspensions for players who test positive for marijuana -- it's still not exactly advocating marijuana use.

"Club medical personnel are prohibited from prescribing, dispensing or recommending the use of marijuana or any other cannabinoid" to players or officials, nor are they allowed to store it at the team facilities, the memo said.

The use of cannabidiol, or CBD, remains potentially risky for players because the products are not certified by the NSF and could be tainted with drugs that are on the banned list and subject to half-season-long suspensions.

MLB and the MLB Players Association "are working closely with NSF International to develop an independent testing and certification process for" hemp-based CBD products, according to the memo.

With the legal-marijuana business worth billions of dollars, players have considered entering the space as entrepreneurs, according to sources. The memo said MLB plans to address the rules regarding ownership in the industry in the future, though "until such guidance is issued, any such investments or commercial arrangements are still considered to be prohibited in accordance with current practices."