In Canada recreational use of cannabis will be legalized on October 17th, however, driving under the influence of marijuana is still illegal. When being pulled over after the alcohol is ruled out as the impairment via breath test, a pulse check, an eye test, one leg stand, and walk and turn test will be conducted. Moreover, in December 2018 Canadian police officers will be able to administer roadside saliva tests. If believed to be impaired, the suspect will be brought back to the police station to complete the 12 step process taking from 30-60 minutes.
https://www.ctvnews.ca/canada/how-police-are-preparing-to-catch-drivers-under-the-influence-of-cannabis-1.3995664