WikiAnswers has a simple explaination:
William Randolph Hearst (Citizen Kane) and the Hearst Paper Manufacturing Division of Kimberly Clark owned vast acreage of timberlands. The Hearst Company supplied most paper products. Patty Hearst’s grandfather, a destroyer of nature for his own personal profit, stood to lose billions because of hemp.
In 1937, Dupont patented the processes to make plastics from oil and coal. Dupont’s Annual Report urged stockholders to invest in its new petrochemical division. Synthetics such as plastics, cellophane, celluloid, methanol, nylon, rayon, Dacron, etc., could now be made from oil. Natural hemp industrialization would have ruined over 80% of Dupont’s business.
Andrew Mellon became Hoover’s Secretary of the Treasury and Dupont’s primary investor. He appointed his future nephew-in-law, Harry J. Anslinger, to head the Federal Bureau of Narcotics and Dangerous Drugs.
Secret meetings were held by these financial tycoons. Hemp was declared dangerous and a threat to their billion dollar enterprises. For their dynasties to remain intact, hemp had to go. These men took an obscure Mexican slang word: ‘marihuana’ and pushed it into the consciousness of America.
A media blitz of ‘yellow journalism’ raged in the late 1920s and 1930s. Hearst’s newspapers ran stories emphasizing the horrors of marihuana. The menace of marihuana made headlines. Readers learned that it was responsible for everything from car accidents to loose morality.
Films like ‘Reefer Madness’ (1936), ‘Marihuana: Assassin of Youth’ (1935) and ‘Marihuana: The Devil’s Weed’ (1936) were propaganda designed by these industrialists to create an enemy. Their purpose was to gain public support so that anti-marihuana laws could be passed.
Examine the following quotes from ‘The Burning Question’ aka REEFER MADNESS:
a violent narcotic.
acts of shocking violence.
under the influence of the drug he killed his entire family with an ax.
more vicious, more deadly even than these soul-destroying drugs (heroin, cocaine) is the menace of marihuana!
Reefer Madness did not end with the usual ‘the end.’ The film concluded with these words plastered on the screen: TELL YOUR CHILDREN.
In the 1930s, people were very naive; even to the point of ignorance. The masses were like sheep waiting to be led by the few in power. They did not challenge authority. If the news was in print or on the radio, they believed it had to be true. They told their children and their children grew up to be the parents of the baby-boomers.
On April 14, 1937, the Prohibitive Marihuana Tax Law or the bill that outlawed hemp was directly brought to the House Ways and Means Committee. This committee is the only one that can introduce a bill to the House floor without it being debated by other committees. The Chairman of the Ways and Means, Robert Doughton, was a Dupont supporter. He insured that the bill would pass Congress.
Dr. James Woodward, a physician and attorney, testified too late on behalf of the American Medical Association. He told the committee that the reason the AMA had not denounced the Marihuana Tax Law sooner was that the Association had just discovered that marihuana was hemp.
Few people, at the time, realized that the deadly menace they had been reading about on Hearst’s front pages was in fact passive hemp. The AMA understood cannabis to be a MEDICINE found in numerous healing products sold over the last hundred years.
In September of 1937, hemp became illegal. The most useful crop known became a drug and our planet has been suffering ever since.
Congress banned hemp because it was said to be the most violence-causing drug known. Anslinger, head of the Drug Commission for 31 years, promoted the idea that marihuana made users act extremely violent. In the 1950s, under the Communist threat of McCarthyism, Anslinger now said the exact opposite. Marijuana will pacify you so much that soldiers would not want to fight.
Today, our planet is in desperate trouble. Earth is suffocating as large tracts of rain forests disappear. Pollution, poisons and chemicals are killing people. These great problems could be reversed if we industrialized hemp. Natural biomass could provide all of the planet’s energy needs that are currently supplied by fossil fuels. We have consumed 80% of our oil and gas reserves. We need a renewable resource. Hemp could be the solution to soaring gas prices.