File photograph of growth technician Mike Lottman moving through the marijuana plants in a medical marijuana center in Denver

 
File photograph of growth technician Mike Lottman moving through the marijuana plants in a medical marijuana center in Denver
Growth technician Mike Lottman moves through the marijuana plants in a medical marijuana center in Denver, Colorado in this April 2, 2012 file photograph. The passage of the ballot measures in Colorado and Washington state in November 2012 allowed personal possession of the drug for people 21 and older. That same age group will be allowed to buy the drug at special marijuana stores under rules set to be finalized next year in 2013. REUTERS/Rick Wilking/Files