OTTAWA—The Canadian Forces are placing limits on when military personnel can use recreational marijuana once it becomes legal, with the restrictions based largely on service members’ jobs and current or upcoming missions.

Supervisors are also being given directions on how to recognize whether their troops might be under the influence, including red or glassy eyes, slow reaction times, anxiety and unusual talkativeness.

The guidelines are contained in a new directive published by the military and are intended to protect the safety and security of troops, equipment and missions while letting troops use recreational marijuana as private citizens.

All military personnel are restricted from using weed eight hours before going on duty, and 24 hours before handling or operating a weapon, servicing a military plane, parachuting or any other exercise or unit training.

The restrictions jump to 28 days for anyone who will be serving on a submarine or as a crew member on a military plane, and all members are forbidden from using the drug during international operations, exercises or training.

Service members who fail to follow the rules or are otherwise suspected of what the directive calls “misusing cannabis” can face disciplinary action or even charges.