Schaffer Library of Drug Policy

Marihuana: A Signal of Misunderstanding

Marihuana and Violence - The Violent and Criminogenic Effects of Marijuana

US National Commission on Marihuana and Drug Abuse

Table of Contents
I. Marihuana and the Problem of Marihuana
Origins of the Marihuana Problem
The Need for Perspective
Formulating Marihuana Policy
The Report
II. Marihuana Use and Its Effects
The Marihuana User
Profiles of Users
Becoming a Marihuana User
Becoming a Multidrug User
Effects of Marihuana on the User
Effects Related to Pattern Use
Immediate Drug Effects
ShortTerm Effects
Long Term Effects
Very Long Term Effects
III. Social Impact of Marihuana Use
IV. Social Response to Marihuana Use
V. Marihuana and Social Policy
Drugs in a Free Society
A Social Control Policy for Marihuana
Implementing the Discouragement Policy
A Final Comment
Ancillary Recommendations
Legal and Law Enforcement Recommendations
Medical Recommendations
Other Recommendations
Letter of Transmittal
Members and Staff
History of Marihuana Use: Medical and Intoxicant
II. Biological Effects of Marihuana
Botanical and Chemical Considerations
Factors Influencing Psychopharmacological Effect
Acute Effects of Marihuana (Delta 9 THC)
Effects of Short-Term or Subacute Use
Effects of Long-Term Cannabis Use
Investigations of Very Heavy Very Long-Term Cannabis Users
III. Marihuana and Public Safety
Marihuana and Crime
Marihuana and Driving
Marihuana - Public Health and Welfare
Assessment of Perceived Risks
Preventive Public Health Concerns
Marihuana and the Dominant Social Order
The World of Youth
Why Society Feels Threatened
The Changing Social Scene
Problems in Assessing the Effects of Marihuana
Marihuana and Violence
Marihuana and (Non-Violent) Crime
Summary and Conclusions: Marihuana and Crime
Marihuana and Driving
History of Marihuana Legislation
History of Alcohol Prohibition
History of Tobacco Regulation
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The Report of the National Commission on Marihuana and Drug Abuse

Marihuana and Violence


The empirical evidence gathered to date lends no support to the hypothesis that marihuana heightens aggressive tendencies in the user or that its effects significantly increase the likelihood of inciting the user to violence or crime. However, those findings summarized below do not mean that marihuana cannot be related to aggressive or violent behavior but merely suggest that the effects of the drug and the behaviors in question may operate independently.

The Mayor's Committee on Marihuana (1944) studied the psychomotor effects of marihuana on 72 prisoners, both users and non-users. Marihuana was administered experimentally as both an oral extract and as cigarettes. The data show that the degree of the drug's effect on psychomotor activities is dependent upon the complexity of the function and, in some cases, on the strength of the dose administered. Although simple reaction time and tasks were only slightly affected, more complex functions like static equilibrium and body and hand steadiness were significantly and adversely affected by both large (5 cc.) and small (2 cc.) doses of the drug.

In contrast to the ability of amphetamines to enhance muscular performance and to increase physical activity (Weiss and Laties, 1962; Tinklenberg and Stillman, 1970), marihuana has been found to decrease the inclination toward physical activity and to actually reduce both physical exertion and activity (Mayor's Committee on Marihuana, 1944; Hollister, et. a]., 1968; Hollister, 1971), thereby decreasing the probability of inciting the user to assaultive behavior.

Although marihuana has been found to reduce inhibitions in some persons, it has not been shown to exaggerate extant aggressiveness to any appreciable degree; in some instances it has, in fact, been shown to reduce aggressiveness, and to induce timidity, fear and passivity in the user (Bromberg) 1934,1939; Chopra and Chopra, 1939; Allentuck, 1942; Chopra, and Chopra, 1942; Charen and Perelman, 1946; Carstairs, 1954; Blumer, et. al., 1967; National Institute of Mental Health, 1970, 1972).

In recent years, a number of studies have been conducted in which marihuana users were asked to describe the effects they experienced while under the influence of the drug. On the whole, their findings are similar to those obtained from the results of laboratory experiments.

Halikas, Goodwin and Guze (1971) found that the majority of the users in their sample reported "usually" feeling relaxed (79%) and peaceful (74%).

Tart (1971) administered a questionnaire to college students in California, one item containing a list of 206 possible effects of marihuana. Respondents were asked to indicate whether, within the last six months, they had experienced the designated effects never, rarely, sometimes, very often or usually. Of the 153 respondents, 69% gave one of the latter three responses to the item: "My inhibitions are lowered so that I do things I'm normally inhibited to do."

To the item: "I lose control of my actions and do antisocial things (actions that harm other people) that I normally wouldn't do," 22% said rarely, 1% said sometimes, and the remaining 77% replied "never." With respect to other more specific effects, 23% of the users stated they "usually" felt physically relaxed, and 49% said they "very often" felt physically relaxed and did not want to get up or move around when high on marihuana (pp. 703-704).

In a study by Brotman and Suffet (1970) of 74 users in New York City (both students and nonstudents) no one mentioned any hostile feelings or actions when asked to describe what happens when they get high on marihuana (p. 264).

Goode (1970) asked 204 respondents to describe their experiences when high on marihuana. Table 1 illustrates the responses of the users to effects possibly related to aggression or crime (pp. 53-54).

In a more recent, Commission-sponsored survey of 15 to 34 year old male residents of Philadelphia, respondents were interviewed about the extent and frequency of their marihuana use, the extent to which marihuana figured in the commission of criminal or delinquent acts and the effects they generally experienced while under the influence of the drug (Goode, 1972). With respect to the effects experienced, nearly all the marihuana users (about 75% of the total sample reported that they had tried marihuana at one time or another) denied that the effects of marihuana on them could be interpreted as criminogenic or violent in nature. Table 2 below presents the subjective effects of marihuana related to crime and violence which were reported by the 559 respondents.


(Figures in Percentages)

More relaxed, peaceful, calmer; marihuana acts as

a tranquilizer - -- ---------------- ------ -- ----- ---------------- 46

Exaggeration of mood: greater subjective impact, emotional significance --- ------ ----- ------------------ -_ -_ 25

Time seems slowed down, stretched out, think more

time has passed ---------- ----------- ------ ---- --------- ------ 25

Become more withdrawn, introverted, privatistic-- - __ 22

Become tired, lazy, lethargic, don't want to move---- - 19

Feel freer, unrestrained, uninhibited --------- ---- --- ------ 18

Feel paranoid ----- ----------- -------- ------ ---------- ----- -- ------- 15

Have hallucinations ---------------------- - -- -- --------- -- ------- 15

Feel sleepy ------ ----------- --- ---- ------------------------------ 14

More uncoordinated, clumsier, motor skills impaired 9

Other people annoy me more; find fault in others ------ 8

Become more active, want to move around more -_ __ - 6


Almost More Less Never

all than than or

Effects reported the half half almost

time the the never

time time

Feeling of wanting to

hurt someone 0 3 96

Feeling of wanting to

do something violent.. * 4 95

Feel more angry 1 3 8 88

Feeling of frustration 3 4 16 78

More willing to follow

others' suggestions 4 12 25 59

Care less what others

think of what you do. . 16 15 10 18

Feeling of being able

to do anything 6 5 13 77

Have hallucinations 9 8 16 66

Feeling of relaxation.... 50 22 10 18

Feel less angry 31 22 13 34

Feeling of drowsiness

or sleepiness 22 25 25 27

* Less than 1/2 of one percent. Source: Goode, 1972: 21.

The data show that the overwhelming majority of the respondents report "never or almost never" experiencing effects which can be characterized as producing frustration, anger, or aggression, and that they usually do not experience effects which could be taken to indicate an increase in suggestibility. On the other hand, substantial proportions of the respondents reported feeling relaxed (72%), less angry (53%) and drowsy or sleepy (47 %, ) at least half of the time.

In sum, these data suggest that marihuana does not commonly produce effects which are likely to increase aggression or incite the user to violence. Numerous studies designed to assess the relationship more directly demonstrate, on the whole, that marihuana does not play a significant role in the commission of violent crimes.

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