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The two memes below make the claim that legalizing drugs will actually lead to a decrease in their use.
Portugal, A Real Land of the Free. In 2001 Portugal decriminalized personal possession of all drugs. Opponents predicted a "parade of horrors". Since 2001 drug use rates in many categories have decreased. Most notable was the large decrease in the 13-19 age group. From 2001-2005 marijuana usage was the lowest in the E.U. Drug-related disease and mortality rates have decreased. There is no serious push to reverse policy as by virtually every metric decriminalization has been a "resounding success". The American government and media have ignored this story. blog.suburra.com Greenwald, "Drug Decriminalization in Portugal" (2009)
Or this popular series of memes:
Portugal's president explains how his country cut drug addition in half: "We decriminalize all drugs and treat addiction as a public health issue instead of a crime -- the opposite of what America does."