Causation vs correlation discussion is just for some people ridiculously hard to understand. But if any argument is made about cannabis causing schizophrenia/psychosis, just tell them they have to ban tobacco, too. There is an abnormally high rate of tobacco use in schizophrenic patients. According to this Wiki article, in 2006 it was near 80% when the general population was at 20%: https://en.wikipedia.org/wiki/Schizophrenia_and_smoking From personal experience, I know that it is definitely above 50% of the people I've met with psychotic illnesses smoke tobacco. That's anecdotal, but still it's very strange. That correlation will pretty much always have a higher rate than any cannabis correlation will ever have (unless it is legalized and people who used to smoke tobacco decided to switch over to marijuana).Cannabis leads to schizophrenia, psychoses, depression, anxiety... They have used it all. One can argue that there exist scientifically proven correlations between cannabis consumption and psychotic events or, in VERY few cases, signs of schizophrenic cognition, BUT the good old "causation and correlation"-discussion has never reached our politicians.