<P> The American Medical Association (AMA) opposed the act because the tax was imposed on physicians prescribing cannabis, retail pharmacists selling cannabis, and medical cannabis cultivation and manufacturing; instead of enacting the Marihuana Tax Act the AMA proposed cannabis be added to the Harrison Narcotics Tax Act . This approach was unappealing to some legislators who feared that adding a new substance to the Harrison Act would subject that act to new legal scrutiny . Since the federal government had no authority under the 10th Amendment to regulate medicines, that power being reserved by individual states in 1937, a tax was the only viable way to legislate marijuana . </P> <P> After the Philippines fell to Japanese forces in 1942, the Department of Agriculture and the U.S. Army urged farmers to grow hemp fiber and tax stamps for cultivation were issued to farmers . Without any change in the Marihuana Tax Act, over 400,000 acres of hemp were cultivated between 1942 and 1945 . The last commercial hemp fields were planted in Wisconsin in 1957 . New York Mayor Fiorello LaGuardia, who was a strong opponent of the 1937 Marihuana Tax Act, started the LaGuardia Commission that in 1944 contradicted the earlier reports of addiction, madness, and overt sexuality . </P> <P> The decision of the United States Congress to pass the Marihuana Tax Act of 1937 was based on poorly attended hearings and reports based on questionable studies . In 1936 the Federal Bureau of Narcotics (FBN) noticed an increase of reports of people smoking marijuana, which further increased in 1937 . The Bureau drafted a legislative plan for Congress seeking a new law, and the head of the FBN, Harry J. Anslinger, ran a campaign against marijuana . Newspaper mogul William Randolph Hearst's empire of newspapers used the "yellow journalism" pioneered by Hearst to demonize the cannabis plant and spread a public perception that there were connections between cannabis and violent crime . Several scholars argue that the goal was to destroy the hemp industry, largely as an effort of Hearst, Andrew Mellon and the Du Pont family . They argue that with the invention of the decorticator hemp became a very cheap substitute for the wood pulp that was used in the newspaper industry . However, Hearst newspapers owed large debts to Canadian suppliers of paper, who used wood as raw material . If an alternative raw material for paper had emerged, it would have lowered the price of the paper needed to print Hearst's many newspapers--a positive thing for Hearst . Moreover, by the year 1916 there were at least five "machine brakes" for hemp and it is unlikely that in 1930s hemp became a new threat for newspapers owners . </P> <P> Mellon was Secretary of the Treasury, as well as the wealthiest man in America, and had invested heavily in nylon, DuPont's new synthetic fiber . He considered nylon's success to depend on it replacing the traditional resource, hemp . </P>

When was hemp made illegal in the united states