Who started the war?
The War on Drugs is a war that, much like the "War on Terrorism" can never be won. The term "War on Drugs" was first used by President Richard Nixon in 1971, but he certainly wasn't the first to campaign against the freedom to use cannabis and other psychoactive substances. Notable in this regard was Harry Anslinger, at the time head of the Federal Bureau of Narcotics, who specifically targeted marijuana.
The War on Drugs is aimed at all drugs with the exception of tobacco and alcohol, which are instead regulated and taxed. In the War on Drugs, no significant distinction is made between addictive and non-addictive drugs, or between harmful and harmless drugs, or whether it's used for escapist reasons or to expand awareness. Nancy Reagan tried to encourage teenagers to "just say no" to all drugs, particularly those that are not taxed or sold by pharmaceutical companies. Her campaign failed miserably, as have all efforts to make people stick to alcohol, tobacco and pharmaceuticals.
A much better approach, supported by most drug users, is to try and prevent harm. This can be done through honest education, handing out clean needles, or for example allowing entrepreneurs to open cannabis dispensaries, so that users don't have to obtain their goods from criminal dealers (a good example being the Dutch "coffeeshop" system, where anyone who's of legal age can obtain a few grams of cannabis).
Supporters of the War on Drugs generally don't care about harm reduction and don't realize their "war" does much more harm than most of these drugs themselves. Especially in the United States, many prison inmates are there because of drug offences. The future of many young students has been ruined because they were busted with a joint.
The War on Drugs is a failure
In 2011 a self-appointed 19-member commission including former UN Secretary-General Kofi Annan, Mexico's former President Ernesto Zedillo, Brazil's ex-President Fernando Henrique Cardoso and former Colombian President Cesar Gaviria, as well as the former US Federal Reserve chairman Paul Volcker and the current Prime Minister of Greece George Papandreou stated: "THE WAR ON DRUGS HAS FAILED". The panel also featured prominent Latin American writers Carlos Fuentes and Mario Vargas Llosa, the EU's former foreign policy chief Javier Solana, and George Schultz, a former US secretary of state.
In 2010 the U.S. federal government spent over $15 billion on the War on Drugs, a rate of about $500 per second.
In recent years many countries have changed their drug laws, most notably Portugal, Czechoslovakia and Peru, decriminalizing the possession of small quantities of various substances. Unfortunately in the Netherlands, for a long time a very progressive country, things have only gone downhill.