Would legalizing and regulating all drugs be more beneficial or more damaging to society?

I was having an argument with someone yesterday about the effects of legalizing all drugs on a society. She was arguing that it would be more damaging while I was arguing that it would be more beneficial. I won't state reasonings as I feel it would best to see what other people come up with on their own.

If you're going to comment, I would like you guys to state reasons why it would be more damaging, more beneficial, or neither. Bland answers like "Its more harmful/beneficial" are pointless, that is what the options are for so please add reasoning, research, sources, etc. Thank you. :)