Insight: Shrinking U.S. labor unions see relief in marijuana industry | Reuters This may speed up legalization.
The Service Employees International Union (SEIU) of California endorsed Prop 19 in 2010: SEIU Endorses California
I heard from a friend who knows a guy who hangs out with union insiders that the teamsters (UPS and others) have already brought up drug policy for teamsters in WA and CO.