Questions and Answers on Cannabis (39 & 27)



Can Increases in Cannabis Use Be Attributed to Reduced Penalties for Possession of the Drug?


Data from individual states where penalties for possession have been reduced do not directly answer this question because adequate baseline date to establish trends pre-dating the legal changes are not available. However, other data — the ongoing annual survey of high school seniors and the national surveys of youth and adult drug use conducted at approximately two year intervals — have been examined for indications of disproportionately increased use of cannabis in groupings of states that have reduced penalties.

Evidence from these two independent sets of data from the U.S. indicates that reducing legal consequences for possession of small amounts of cannabis does not accelerate the growth rate in use. Preliminary results from the high school seniors study showed that increases in marijuana use in states that had “decriminalized” possession of small amounts, taken as a group, were equal to or less than increases observed in the rest of the country where “decriminalization” was not taking place. The national youth and adult drug use survey data show that growth of marijuana use was slowest among states which reduced the penalties for possession in the mid-1970’s, and most rapid among those maintaining severe legal regimes. Generally, use was already highest, but grew more slowly, in those states which reduced penalties; however, it was lowest and grew more rapidly in those states which kept more severe penalties for possession.

With respect to the long-term effects of reducing penalties for possession of cannabis, U.S. data indicate that persons in states having moderate cannabis penalties may begin to use cannabis later in adolescence, and continue to use if further into adulthood, than persons in states having severe penalties. However, increases in usage (although not in the rate of increase in usage) may be expected, regardless of penalty.


L. Johnston, “Marijuana Use and the Effects of Marijuana Decriminalization,” Testimony to the Sub-Committee on Criminal Justice, Judiciary Committee, U.S. Senate; January 16, 1980.

W. Saveland and D.F. Bray, “Trends in Cannabis Use Among American States with Different and Changing Local Regimes, 1972-77,” Health Protection Branch, Health and Welfare Canada, 1980.



Has cannabis use increased since decriminalization?


Three U.S. states have surveyed the extent of marijuana use following decriminalization.

In the four years since Oregon eliminated criminal penalties for simple possession (1974-1977), the number of adults who claim to have ever used marijuana has increased 6% and the number who claim to be current users has increased 1%. The usage trends previous to the reform legislation are unknown.

California compared usage at five months before and at seventeen months after decriminalization. A 7% increase was found in the number of adults who reported having ever used marijuana. Those considering themselves current users rose 5%, although their frequency of use decreased.

A Maine survey of high school and adult users found that, at two years after decriminalization, 48% of the adult users had decreased their usage, 13% reported an increase and 39%, little or no change. Twenty-six percent of high school users claimed a decrease in use, while 38% reported an increase and 36%, little or no change.

American data indicate that increases in marijuana use are most rapid among states which maintain relatively severe penalties (i.e., substantial fines or imprisonment) for possession of small amounts.


Drug Abuse Council, Washington, D.C. Survey of Marijuana Use and Attitudes, State of Oregon, 1978.

California State Office of Narcotics and Drug Abuse. A First Report on the Impact of California’s New Marijuana Law (SB 95). January, 1977, p. 10-11.

State of Maine. Office of Alcoholism and Drug Abuse Prevention. An Evaluation of the Decriminalization of Marijuana in Maine, 1978.

Special tabulations of American national survey data prepared for the Bureau of Tobacco Control and Biometrics, Health Protection Branch, Health and Welfare, Ottawa, by the Drug Abuse Epidemiology Data Centre, Texas Christian University, Port Worth, 1980.

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