In the US the consequences will vary depending on what state you live in. In upstate NY, sitting in traffic court for an evening I learned that every single case for 'possession' (all small amounts - not 'intent to distribute') was given a $50 fine and nothing on their record.
What would the 20's have been if everyone was too scared to go to a speakeasy?
The actual NY state law as explained by NORML: "Possession of 25 grams or less of marijuana is punishable by a fine of $100 for the first offense." 25g is .88 ounces, which is what a recreational smoker might consume in an entire year. It's worth noting though that the punishments are much harsher if you get caught smoking or displaying weed in public.
What would the 20's have been if everyone was too scared to go to a speakeasy?