Marijuana has a complex history of legality that varies by jurisdiction. For various reasons, it was made illegal in many countries in the early to the mid-20th century. Some key factors that contributed to the criminalization of marijuana include:

  1. Racism and xenophobia: In the early 20th century, marijuana use was associated with Mexican immigrants and African American communities in the United States. Racist and xenophobic sentiments played a role in stigmatizing cannabis use and promoting negative stereotypes. This led to the portrayal of marijuana as a dangerous drug believed to incite crime and immoral behavior.
  2. Misinformation and propaganda: During the early 1900s, sensationalist media and propaganda campaigns, such as the film “Reefer Madness,” spread misinformation about the effects of marijuana. This contributed to the perception that marijuana was a dangerous and addictive drug that could lead to insanity, criminal behavior, and social deviance.
  3. Economic and political interests: Some industries, including the paper, textile, and pharmaceutical industries, viewed marijuana and hemp (a non-psychoactive variety of the cannabis plant) as potential competitors. By criminalizing marijuana, these industries protected their economic interests. Additionally, some political figures saw the opportunity to capitalize on anti-marijuana sentiments to advance their careers and agendas.
  4. International drug control efforts: In the early 20th century, international efforts to control drug use and trafficking led to the inclusion of marijuana in various drug control treaties. The 1961 Single Convention on Narcotic Drugs, an international treaty, classified marijuana as a Schedule I drug, meaning it was considered to have a high potential for abuse and no accepted medical use. This classification led to the criminalization of marijuana in many countries.
  5. Lack of scientific research: Early research on marijuana was limited, and many claims about its dangers were based on anecdotal evidence or flawed studies. As a result, lawmakers and the public were not well-informed about the potential risks and benefits of marijuana use. This lack of reliable information contributed to the perception that marijuana was a dangerous and addictive substance.

Over the past few decades, public opinion on marijuana has shifted significantly, and many countries and states have moved toward decriminalization or legalization for medical and recreational use. This shift has been driven by changing cultural attitudes, increased scientific research on the potential benefits and risks of marijuana use, and the recognition of the negative social and economic consequences of marijuana prohibition.