That’s a very US centric view. Not all research is conducted inside the US. Drug laws around the world vary. http://scholar.google.com/scholar?q=netherlands+schizophrenia+cannabis&hl=en&as_sdt=0&as_vis=1&oi=scholart&sa=X&ei=JuJQU8idEoOb0QXPlIDYBg&ved=0CCUQgQMwAA
Is just the first example that came to mind.
