2009 marks the culmination of Portugal's 8 year study in drug decriminaliztion. Result: Decriminaliztion lead to less drug use. I really cant see this not happening at some point in the UK and other countries...

http://www.time.com/time/health/article/0,8599,1893946,00.html

Any sort of war on drugs is just fighting a losing battle anyway. Its hard to see what the main argument against decriminalization actually is.