Stiff competition from thousands of mom-and-pop marijuana farmers in the United States threatens the bottom line for powerful Mexican drug organizations in a way that decades of arrests and seizures have not, according to law enforcement officials and pot growers in the United States and Mexico.
Illicit pot production in the United States has been increasing steadily for decades. But recent changes in state laws that allow the use and cultivation of marijuana for medical purposes are giving U.S. growers a competitive advantage, challenging the traditional dominance of the Mexican traffickers, who once made brands such as Acapulco Gold the standard for quality.http://www.cbsnews.com/stories/2009/10/07/politics/washingtonpost/main5368594.shtml
So, let's see here... Violent evil gangs in Mexico get screwed over, and the price of weed goes down for everyone in the USA.
I'm having a hard time seeing any downside here. ;]