[netcan]

There are several arguments that independently could justify legalization: (1) criminalization creates an enormous ($350b) criminal economy with associated increase in criminal activity. (2) Legal drugs contribute the formal economy, taxes, etc. (3) People should have the right to decide for themselves what drugs they take. (4)The war on drugs has failed to substantially reduce supply. (5) Drugs are safer when legal (6) Cannabis isn't really harmful, it's sometimes beneficial

Of these, only 6 is cannabis specific. The rest are true regardless of the drug. Many pro-legalization people argue that demand/consumption will not increase because of legalization (I disagree). Even if you think consumption will go up (most economists do because of higher quality, lower prices and reduced stigma) you might think that one or more of those 5 reasons to legalize still outweigh the alternative.

Once this stuff is on the agenda it's only natural that it gets looked at more broadly. It's like free trade agreements leading to free trade zones or unilateral reductions of trade barriers.