It's realistic that it would be proposed but it's too impractical, unless of course people could get licenses to prove they are allowed to use drugs.
I know this is off topic but I hate those posters that say stuff like marijuan shouldn't be used because it's illegal. I think I may have read this in Lies My Teacher Told Me: Because it is illegal is no reason why drugs are bad.
It's cause and effect but used wrong.
Marijuana is bad (let's just say that is the actual reason). Therefore it is illegal. That doesn't mean it's bad because it's illegal; it means it illegal because it's bad.