Legalize all of them and sell them out of Government Drug Stores, only pure product at rock bottom prices (perhaps even subsidize it), get the money while cutting the illegal dealers out of the business.
1: Put the illegal dealers out of business
2: Keep all the money for the Treasury.
3: Pure product guarantees more OD’s
4: Darwin awards to all of them.
Opposite - a significant source of ODs is unexpectedly high purity; if purity is standardized, the user will always know what they're getting.