We have many proven methods for reducing the demand for drugs. Keeping drugs illegal reduces their availability and lessens willingness to use them. That is why this Administration firmly opposes the legalization of marijuana or any other illicit drug. Legalizing drugs would increase accessibility and encourage promotion and acceptance of use. Diagnostic, laboratory, clinical, and epidemiological studies clearly indicate that marijuana use is associated with dependence, respiratory and mental illness, poor motor performance, and cognitive impairment, among other negative effects, and legalization would only exacerbate these problems.
-- Barack Obama, "2010 National Drug Control Strategy"