Continuing with the current prohibition causes much more harm than good.
It causes civil wars, and other widespread crime and violence not only in America, but in other countries. Look at the situation in Mexico right now, and the problems Colombia has been dealing with for decades.
http://www.cnn.com/2009/WORLD/americas/02/04/mexico.general/index.html
200 drug related murders in Juarez Mexico in 2009 alone.
As for pot, I say legalize it ASAP, tax it and end the drain on the justice system and lives and careers heavily impacted over something that is mainstream in America and is not going away. I thought America had learned its lesson on prohibition.
As for the other hard drugs, I dont have a great answer, but billions of dollars in cold hard cash leaving America and going to criminals and terrorist organization isnt the best way to deal with this. Imagine if we could deal with addiction responsibly, free up law enforcement/military assets for other things and ending a multibillion dollar illegal industry.