It has recently been reported in several news sources that places where access to marijuana has been legalised have seen significant decreases in the use of other, more dangerous, drugs.
In an article arguing that a more relaxed approach to medical marajuana could save the US government a large amount of money, Forbes reports, for example:
...states with legalized medicinal marijuana laws saw significant drops in prescriptions for pain medication, as well as for antidepressants, seizure medication, anxiety medication, sleep aids, and anti-nausea drugs, among others.
Given the normal governmental attitude to recreational pharmaceuticals, this seems likely to be controversial. Is it true that access to marijuana can reduce the use of other drugs significantly?