A study by Glenn Greenwald found that in the five years after the start of decriminalization , illegal drug use by teenagers had declined , the rate of HIV infections among drug users had dropped , deaths related to heroin and similar drugs had been cut by more than half , and the number of people seeking treatment for drug addiction had doubled , while usage in the EU continued to increase , including in states with `` hard-line drug policies . ''
Glenn Greenwald worked at the Cato Institute .