Schaffer Library of Drug Policy

Marihuana: A Signal of Misunderstanding

Marihuana and Violence - Opinions About Marihuana and Aggressiveness

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


Several references have already been made to anecdotal case histories, to the claims made and to the opinions formerly held by a number of law enforcement authorities relative to the relationship between marihuana use and aggressive behavior or violent crime. A few systematic efforts have been made to explore the current opinions and attitudes of law enforcement and criminal justice officials.

Probably the first detailed survey of the opinions of police officers was that conducted by a Stanford University law student in 1968. Part of this unpublished study has been summarized by Kaplan (1971) and is reprinted below.

Law enforcement agencies have continuously supported the existence of a strong causal relationship between the use of marijuana and acts of aggression and violence. In order to determine the nature and basis for this belief, sixteen law enforcement and narcotics officers were interviewed. The officers selected for the interview from each pollee department were those who spent the largest percentage of their time actually working with marijuana users. When the department had several officers working full time on narcotics, the officer In charge was interviewed, on the supposition that as chief officer, he would have the longest and widest range of experience with marijuana users.

Of those interviewed, seven spent 100% of their time on narcotics problems; three spent 75% to 100%; I spent about 50%; and the remaining five spent 10% to 25%. All emphasized that of their narcotics work, a major proportion of the time is spent on marijuana problems.

The context in which the officers observe individuals under the influence of marijuana is an important factor in evaluating their observations. Only three had done stakeout work where conduct could be observed while under cover. The remaining thirteen officers had only encountered marijuana users in either arrest or questioning situations. In response to the question of whether they had opportunities for informal contact with people using marijuana while off duty or in a social situation, the officers uniformly answered, "no."

The specific subject of this project, i.e. marijuana and aggression, was never mentioned to the officers. They were told only that I was interested in the marijuana question. The first question which I asked was to briefly characterize, from their per8onal experience and observations, the behavior of individuals while under the influence of marijuana. During this original description, 10 of the officers mentioned violence or aggressive behavior as a common characteristic. The six other officers didn't mention aggression as a distinguishing characteristic in their original description however, in the next question, when specifically asked if marijuana does lead to aggressive behavior, all said that it did.

Every one of the officers pointed out the wide range of conduct which they see exhibited by those that are "high" on marijuana. They emphasized that how a person reacts depends on his particular personality. As one officer commented, "Some individuals are very happy and to them everything is beautiful, while others are always looking for a fight." Six (6) of the officers emphasized how quickly they can see one mood change into the other-at one moment docile and passive, at another extremely aggressive.

A few of the officers commented that along with the direct influence of marijuana, another important factor in aggressive behavior Is the arresting situation. One officer, Lieutenant A of the B Police Department, who has done quite a bit of stake-out work as well as undercover investigation, pointed out that this change from "silly, joking, funny and talkative" moods to apprehensive and often aggressive postures is many times precipitated by the realization that a law enforcement officer is present.

Sergeant C of the D Police Department also felt the "arresting situation" was probably the primary factor in aggressive behavior reports about marijuana users. Sergeant E also mentioned "the approach of a known policeman" as a factor in the aggressive behavior which they see. However, Sergeant E also estimated that one fifth

of the males, when under the influence of [marijuana] and when aware that they are being arrested, will break and run or resist. This he feels is a much higher percentage than for other types of arrests. Similarly most of the officers did maintain that even considering all other factors such as arrest, the marijuana was the force in most cases which was responsible for the aggression and violence.

Mr. F of the G County Sheriff's Office, however, maintained that in the last few years, those arrested for marijuana offenses have tended to resist arrest less often than previously. He stated, "They now feel they don't have to fight the officers because of the laws-because of legalizing attempts, they feel they don't have to fight, for they will have their day in court."

Sergeant H of the I Police Department stated that recently (within the last year) he has seen no aggressive reaction to marijuana because of the extremely weak grades of marijuana now available. He felt that the determinative factor in how a person reacts while "high" is the strength of the grass smoked. He reported that the grass they have recently been finding has a very low resin content and its effects are merely "a quick stimulant followed by a depressed mood." However, in another part of the interview, when discussing the type of personality prone to using marijuana, Sergeant H distinguished between those now smoking and the "old grasshead." These latter were, only "Spanish-American or criminals." Now, however, "people without criminal records are joining the ranks of criminals." This major shift in the personality type now using marijuana, it would seem, would be another factor leading to Sergeant H's observation that the problems with aggressive reactions have decreased.

While all stated their belief that marijuana does lead to aggressive behavior, it was in most cases very difficult to elicit from the officers any specific instances where they personally had observed an aggressive reaction to the use of marijuana. Four (4) officers stated that they had never personally seen someone aggressive under marijuana. They all, however, had heard reports of such instances from other officers. It should be noted also, that these four officers are from small police departments located chiefly in middle class residential areas.

Me officers who did cite specific examples of aggressive behavior from their personal observations cited such conduct as individuals who possessed marijuana fighting among themselves, cases of resisting arrest, a [man] picking a fight in a bar, beating one's wife, sexual promiscuity, stealing, reckless driving, and carrying knives and guns. While citing this type of example most officers emphasized the real difficulty in telling when someone is "high." Except for a few symptoms such as red or dilated eyes, they have to make the judgment from the general actions of the subject. When the subject is acting peculiar and there is no alcohol, or they find marijuana in his possession, then they assume he is "high."

It was also difficult to limit these discussions solely to marijuana. When asked for personal case histories, they often recounted incidents of individuals who had also been using other drugs or alcohol in combination with marijuana. The officers tend to group all of the drugs together, and discuss them together in generalities applying to all. One officer, from J County, recounted as one of his -personal experience histories with aggression and marijuana, a boy who went "berserk" on Christmas day, and who finally had to be shot by the police. On checking newspaper accounts, it appears that LSD was also involved in the episode.

The officers all indicated that they have personally seen many aggressive reactions to the use of alcohol. Most, however, did not feel they could compare the frequency with that of marijuana. Most deal mainly with narcotic problems and thus spend most of their time with marijuana problems. The alcohol problems, and specifically the aggressive or belligerent drunk, are handled by the "beat" cops.

It was also difficult to limit the discussion to personal experiences of the officers themselves. Many of them, when asked for specific examples, went immediately to their desks for reports and articles issued by other law enforcement agencies. This it seems is a problem which developed because of the sample chosen to interview. Because they were usually the most experienced and the chief narcotics officers, most of them are called upon to give speeches before PTA's, church groups, school classes, etc. They all, therefore, were familiar with the literature distributed by law enforcement....

Three of the officers cited as proof of marijuana's danger a recent distribution which pointed out that the "death penalty" Is now imposed on marijuana offenders in Nigeria.

When questioned on passive reactions to marijuana, all of the officers could think of personal encounters with people who were "high" and who were decidedly passive and docile. Yet only four of the officers included this trait in their original characterization of behavior under marijuana. Eight of the officers, however, in their original description of behavior while "high" described some persons as "happy," "funny," or "giggly."

One question asked of the officers was aimed at differentiating the aggressiveness (chiefly in terms of frequency of resisting arrest) between those "high" on marijuana and those arrested for sale or for possession. As mentioned previously, the officers indicated that generally they have a very difficult time distinguishing those who are "high." The officers interviewed generally work on [arresting] pushers, and dealers. Their attention is usually not drawn to individuals because of the particular conduct they might be exhibiting, but rather because the individual is dealing in marijuana. When pot parties where everyone is high have been [broken up], Sergeant 0 of D reported that the places raided have usually been on the peaceful side. Another officer, K, on the narcotics detail in D, felt that users are usually "very easy to arrest. With others, such as pushers, and sellers, however, officers have to -be more careful." Captain L of M disagreed, however, maintaining that those under the influence must be watched more closely and are usually more aggressive and violent because of a lessening of concern for the consequences and a lack of ability to make sound judgments. Deputy Chief N of the 0 Police Department pointed out that In 0 at any rate, there is a certain "show" which those arrested feel they must put on; "it is hard to separate this show from the effects of the marijuana," Lieutenant P of the 0 Police Department said his experience indicated that those under the influence had to be watched closely. He has arrested people, [when they were] "high" three of four times without incident; the fifth time, however, he felt they might go wild.

In response to a question of whether they felt that some persons smoke pot before engaging in crimes against property, such as robbery, ten of the officers replied that they did believe that this occurred often. Seven of these could cite specific examples of people who had been picked up for stickups, car thefts, etc. and who reported using marijuana beforehand to bolster their courage, or sharpen their senses. However, the other three of the ten had only heard of such conduct. The remaining six officers answered that they did not think this was common, and had never seen any examples. . . .

None (of the officers) believed however that marijuana was responsible for any long-term effects resulting in aggressive behavior. The relationship between marijuana and aggression, they feel, is limited strictly to the period of time during which the user is under the influence. In terms of long-range effects of marijuana on aggression, the reactions of the officers confirm that, if anything, there is a negative correlation. That is, marijuana leads to nonaggressive, non-competitive, passive conduct, when viewed in the context of chronic use.

Whatever limitations and qualifications one can cite regarding the conclusions drawn by law enforcement officers, one thing remains certain: they do believe that the use of marijuana leads in a significant number of cases to aggressive behavior (Kaplan, 1971, citing Schofield: 110-115).

In seeking to present to the public as much information about marihuana and its effects, from as many different sources and approaches as possible, the Commission sponsored the design and execution of two opinion surveys of the criminal justice Community. In addition to soliciting their current opinions about the relationship of marihuana to aggressive or violent behavior, and to infer from them the extent to which their professional experience with marihuana users may have changed over the years, the Commission sought to determine the extent to which current opinions and attitudes of the criminal justice community reflect the growing body of empirical evidence on the subject.

To these ends, nationally representative samples of prosecuting attorneys, judges, probation officers and court clinicians were surveyed by mail. The questionnaires mailed to these officials contained items relative to the relationship between marihuana use and aggressive or violent behavior. The results of these surveys show that more than three fourths of the 781 judges, probation officers and court clinicians responding to a mail survey (InTech, 1971) regarded as either questionable or " probably untrue" the statement that "most aggressive acts or crimes of violence committed by persons who are known users of marihuana occur when the offender is under the influence of marihuana. More than 60% however, regard as equally questionable or untrue the statement that most such aggressive acts or crimes of violence occur when the offender is not tinder the influence of the drug but is attempting to obtain it or the money to buy it. Table 3 shows the percentage of each of the three groups of respondents answering in this manner. (InTech, 1971).

These figures give the impression that neither judges, probation officers nor court clinicians are certain of the role of marihuana in the commission of violent crime. Their tendency to deny both statements suggests that at the least, the relationship, to the extent that it does exist, is a tenuous one.


(Figures in Percentages)

A. "Most aggressive acts or crimes of violence committed by persons who are known users of marihuana occur when the offender is under the influence of marihuana.',

Probably Probably Not sure

true not true

Judges 17.3 44.2 29.5

Probation officers 14.5 60.0 21.8

Clinicians 6.1 76.5 13.0

Total 15.2 51.2 26.0

B. "When the offender is not under the influence of marihuana but is attempting to obtain marihuana or the money to buy it."

Probably Probably Not sure

true not true

Judges 35.6 30.6 25.0

Probation officers 27.3 44.5 21.8

Clinicians 20.0 60.9 15.7

Total 32.1 37.0 23.2

In its survey of state prosecuting attorneys, the Commission likewise found a tendency for these officials to deny a causal relationship between marihuana use and aggressive behavior; 52% of the respondents stated that they either did not believe or were uncertain about the proposition that use of marihuana causes aggressive behavior. Of those who did believe in a causal relationship, however, two-thirds of the respondents' beliefs stemmed front other than personal observation of aggressive behavior exhibited by marihuana users.

These opinion surveys reveal that at least these members of the criminal justice community have begun to reexamine their earlier beliefs. The data suggest that, in their professional experience, they have not found marihuana users to be aggressive or violent to such an extent as to elicit strong and consistent opinions about the causal relationship between marihuana use and violence.

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