"Switzerland’s progressive implementation of the Four Pillars policy resulted in a significant decrease in problems related to drug consumption. The rise in heroin consumption, by far the greatest problem in the late 1980s, was halted and has steadily declined since the early 1990s. According to The Lancet, the The introduction of the Four Pillars strategy also brought about a significant reduction of deaths directly attributable to drug use, such as overdose (OD), and of deaths indirectly related, such as HIV and Hepatitis. Between 1991 and 2004, the drug related death toll fell by more than 50% (See figure 3). Additionally, levels of drug-related HIV infection were divided by eight within ten years."

Source

Savary, Jean-Félix; Hallam, Chris; and Bewley-Taylor, Dave, "The Swiss Four Pillars Policy: An Evolution From Local Experimentation to Federal Law," The Beckley Foundation Drug Policy Programme (Beckley Park, Oxfordshire, UK: May 2009), p. 5.
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