Medical cannabis users have a defence for the 2mcg/L THC limit, yet you must...

https://www.pop-bookmarks.win/legally-prescribed-cannabis-doesn-t-grant-a-free-pass-on-the-road-while

Medical cannabis users have a defence for the 2mcg/L THC limit, yet you must still meet DVLA fitness-to-drive rules. Legality isn't a substitute for responsibility; being prescribed doesn't exempt you from impairment laws