IN THE OLD DAYS, when cops found weed in your car they’d charge you with possession of a controlled substance. NOW they charge you with impaired driving. IN THE OLD DAYS cops needed a reasonable suspicion to demand a breath sample. NOW breath demands are mandatory and arbitrary.

Vancouver lawyer Sarah Leamon points out that there's been no flood of weed-fuelled motorists on the roads since cannabis was legalized.
https://www.straight.com/news/sarah-leamon-feds-mostly-missed-mark-with-changes-to-impaired-driving-laws