I'm gonna play devil's advocate to legalizing drugs for a minute.

What put Al Capone in jail? Taxes. It wasn't really what he was guilty of - as far as violence on society - but it put him in Alcatraz till he died.

How many violent gang members are arrested on drug charges just because they can't be convicted on their real crimes against society?

Do you want to take away a viable convictable offense/tool in stopping crime?

Start thinking about it. These are only a couple of examples off the top of my head. I can think of a whole bunch more.