March 18, 1839: Lin Tse-Hsu, the imperial Chinese commissioner in charge of suppressing the opium traffic, orders all foreign traders to surrender their opium. In response, the British send expeditionary warships to the coast of China, initiating the First Opium War.

March 14, 1937: Setting a judicial precedent important to drug policy, the US Supreme Court rules that machine guns can be controlled by first taxing them, then using the tax act to prohibit them. One month later Harry Anslinger, head of the Federal Bureau of Narcotics, introduces the Marijuana Tax Act to Congress.

March 12, 1998: Canada legalizes hemp production and sets a limit of 0.3% THC content that may be present in the plants and requires that all seeds be certified for THC content.

March 12, 1998: The mayors of San Francisco, Oakland, Santa Cruz and West Hollywood write letters to President Clinton asking him to keep the cannabis buyers' clubs open. They tell the president: "If the centers are shut down, many of these individuals will be compelled to search back alleys and street corners for their medicine," and ask him to "implement a moratorium on enforcement of federal drug laws that interfere with the daily operation of the dispensaries."

March 17, 1999: A report by the Institute of Medicine for the Office of National Drug Control Policy states that "there is no conclusive evidence that the drug effects of marijuana are causally linked to the subsequent abuse of other illicit drugs" and "scientific data indicate the potential therapeutic values of cannabinoid drugs for pain relief, control of nausea and vomiting, and appetite stimulation."

March 16, 2000: Patrick Dorismond, an unarmed security guard, is shot and killed by undercover New York City police officers who had unsuccessfully tried to sell him marijuana in a "buy-and-bust" operation. [The shooting was the third time in 13 months that New York City police officers dressed in plainclothes shot and killed an unarmed black man. Under Mayor Rudolph Giuliani, marijuana arrests rose from 720 in 1992, to 59,945 in the first eleven months of 2000.]