If possessing it is decriminalized and legitimate sources aren't made a more attractive option than otherwise, then people are still going to end up supporting cartels etc. when buying it.
Legalization changes that because it makes it a lot easier to cultivate in the US, safely and legally.
Illegality encourages actions like smuggling from Central and South America, and guerrilla grows in National Forests. With decreased legal pressure, more savory elements of society produce high quality cannabis in the US.
So, even if that produce is sold on the black market its a better situation than violent gangs from Mexico smuggling bricks of marijuana with theI meth, cocaine and heroin.
Probably pot should just be completely legalized and made into a taxable commodity like alcohol. Kill it as a revenue source for gangs.
One thing, though; when it's illegal, police find it a convenient way to bust a known baddie and get them off the streets. Take that away and they lose a valuable tool.
