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Marihuana, A Signal of Misunderstanding


The Report of the National Commission on Marihuana and Drug Abuse

Marihuana and Violence

(The evidence to be presented here applies not only to aggression and to violence but to marihuana's relationship to crime in general, and is therefore equally relevant to a later section on marihuana and non-violent crime. The effects of marihuana on sexual behavior, including the commission of sexual offenses will be treated in the following section on marihuana and sexual behavior.)



The popular and professional literature contains numerous unsupported and often emotionally charged accusations regarding marihuana's contribution to violence.

In at least two dozen comparatively recent eases of murder or degenerate sex attacks, marihuana proved to be a contributing cause (Anslinger, 1937).

In a recent study of thirty-seven murders in New Orleans in a year, seventeen were traced directly to marihuana. . . . Evil marihuana is pock-marking this nation with murders, sex attacks, suicides, and crimes in every category from bank stick-ups to petty thievery . . . (LaRoe, 1940).

Marihuana, while giving the hallucinations of cocaine, adds delusions of impending physical attack by one's best friend or close relatives. In addition, marihuana is intrinsically and inherently crime exciting. It has led to some of the most revolting cases of sadistic rape and murder of modern times (Rowell and Rowell, 1939: 67).

Even sex does not satisfy the abnormal urges induced by marihuana. There is still the necessity for further excitement, more emotional release. That is when the guns are grabbed, the knives waved and the razors swung. And all that is a marihuana user's idea of what is normal! (Williams, 1969).

To add greater credibility to their undocumented assertions, some persons describe the manner in which the drug purportedly leads to violence.

In the earliest stages of intoxication the willpower is destroyed and inhibitions and restraints are released; the moral barricades are broken down and often debauchery and sexuality result. Where mental instability is inherent, the behavior is generally violent. An egotist will enjoy delusions of grandeur, the timid individual will suffer anxiety, and the aggressive one often will resort to acts of violence and crime ... (Anslinger and Tompkins, 1953: 22).

Smoking of the weed is habit-forming. It destroys willpower, releases restraints, and promotes insane reactions ... Robberies, thrill murders, sex crimes and other offenses result (New York Daily Worker, 1940, in Solomon, 1968: 288).

Others simply deny these allegations or assert that there is no evidence to support the thesis of an independent causal relationship.

The fact that so many witnesses testified to the peaceable and orderly character of the excessive consumers goes far to prove that in this country experience shows that as a rule these (hemp) drugs do not tend to violent crime and violence (Indian Hemp Drugs Commission, 1969: 258).

A fair summary of the available evidence would be that very rarely do major (particularly violent) crimes follow upon the use of the drug, and that, in instances where they do, the relationship is an indirect one (Ausubel, 1958: 103).

One likely hypothesis is that, given the accepted tendency of marihuana to release inhibitions, the effect of the drug will depend on the individual and the circumstances. It might, but certainly will not necessarily or inevitably, lead to aggressive behavior or crime (President's Commission on Law Enforcement and Administration of Justice, 1967: 13).

The relationship between marihuana use land the commission of aggressive acts or violent crime such as murder, rape and assault remains one of the most controversial issues relating to the drug. Persons who believe that such a relationship exists often argue that marihuana triggers the release of inhibitions and restraints, destroys the will power and heightens aggressive tendencies of the user, serving as a catalyst for the commission of aggressive or violent acts.

This argument raises several fundamental questions: Are the effects presumably induced by the drug commonly experienced by marihuana users? Are these effects, to the extent that, they do occur, generally or frequently translated into overt behavior? And is the behavior which presumably manifests itself ordinarily violent or aggressive?

The answers to these questions may be obtained from several sources, including the results of laboratory experiments designed to measure certain physiological and psychological reactions and to identify observable behavioral effects; and retrospective self-reports of effects purportedly experienced by marihuana users. Additional clues may be gained from examination of the criminal records of known marihuana users and the incidence of marihuana. use among persons arrested for or convicted of violent crimes. However, while these latter methods may reveal statistical associations (which could prove to be spurious upon further analysis), they should riot be interpreted to demonstrate the existence of a causal connection between marihuana use and the offenses committed.


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 Dot 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.


Over the years a number of approaches have been utilized in an effort to assess the relationship between marihuana use and violent crime. Perhaps the simplest approach is to compile a. list of violent offenses allegedly committed by marihuana users and to establish, retrospectively, the role of marihuana in the commission of these offenses.

The Indian Hemp Drugs Commission (1894), for example, investigated 81 cases of violence allegedly caused by hemp drugs in in effort to determine whether or not a causal relationship existed. Of these 81 cases, 11 were too old to permit adequate investigation. In 23 of the cases examined, however, 18 showed no evidence of a connection between the crimes and the use of hemp drugs. The Commission concluded that:

In respect to his relations with society, however, even the excessive consumer of hemp drugs is ordinarily inoffensive,. His excesses may indeed bring him to degraded poverty which may lead him to dishonest practices; and occasionally, but apparently very rarely indeed, excessive indulgence in hemp drugs may lead to violent crime. But for all practical purposes it may be laid down that there is little or no connection between the use of hemp drugs and crime (Indian Hemp Drugs Commission, 1893-1894, reprinted 1969: 204).

Similarly, in 1938 the Foreign Policy Association published the accounts of 10 marihuana crimes, including murder and assault, "culled at random from the files of the U.S. Bureau of Narcotics" (Merrill, 1938: 28). These cases were presented in such a way as to imply that marihuana caused the offenses. According to Grinspoon (1971: 302), they "gave the reader the distinct impression that the -user of marihuana was a violent criminal who was given to rape, homicide, and mayhem." Bromberg (1939), however, questions the validity of the causal assumption.

It is difficult to evaluate these statements, because of their uncritical nature.... Among the ten patients, the second, J. O., was described as having confessed how lie murdered a friend and put his body in a trunk while under the influence of marihuana. J. 0. was examined in this clinic (Bellevue Hospital) ; although lie was a psychopathic liar and possibly homosexual, there was no indication in the examination or history of the use of any drug. The investigation by the probation department failed to indicate use of the drug marihuana. The deceased, however, was addicted to heroin (p. 9).

Based on retrospective case analyses, some observers have attempted to specify more precisely. the nature of the purported relationship or the situations in which aggressive behavior may result from marihuana use. Bromberg (1939), for example, suggested that aggressive or violent behavior may arise when a naive subject develops a panic state in response to marihuana-induced hallucinations. Allentuck and Bowman (1942) believed that aggressive or antisocial behavior following use may occur as a reaction to some unpleasant external stimulus during the phase, of hypersensitivity and heightened psychomotor activity. Others have suggested that antisocial conduct of an aggressive or violent nature may occur when marihuana is used, as alcohol often is, to release repressed feelings of hostility (Siler, et al., 1933; Chopra and Chopra, 1939; Allentuck and Bowman, 1942; Freedman and Rockmore, 1946; Murphy, 1963), and to serve as a fortifier for aggressive or violent crimes (Ewens, 1904; South Africa Interdepartmental Committee on Abuse of Dagga, 1952; Ames, 1958; Watt, 1961; Blumer, et al., 1967; Miller, 1968).

The available evidence bearing on these issues, however, suggests that panic reactions rarely occur; that psychomotor activity is more often reduced than enhanced following use; that aggression rarely follows use, but when it does, it generally occurs among individuals with histories of maladjustment, emotional instability or impulse disorders (Bromberg, 1934, 1939; Charen and Perelman, 1946; Ausubel, 1958; Bloomquist, 1968; Grinspoon, 1971; Kaplan, 1971; National Institute of Mental Health, 1972).

After a series of studies of marihuana and crime, Chopra and Chopra (1939) concluded that if any relationship existed between marihuana use and violent crime, it was an indirect one. They stated that:

So far as premeditated crime is concerned, especially that of a violent nature, hemp drugs . . . may not only not lead to it, but they actually act as deterrents.... One of the, important actions of these drugs is to quieten and stupify the individual so there is no tendency to violence. . . . The result of continued and excessive use of these drugs in our opinion is to make the individual timid rather than lead him to commit a crime of a violent nature (p. 92).

Over the years, the conclusion of the Chopras has received increasing support from many quarters of the research community (Mayor's Committee on Marihuana, 1944; Maurer and Vogel, 1962; White House Conference on Narcotic Drug Abuse, 1962; Murphy, 1963; President's Commission on Law Enforcement and Administration of Justice, 1967; National Institute of Mental Health, 1970, 1972).

In the absence of possibilities for addressing the issue more directly, several researchers have relied on statistical studies and have sought to establish the overall and comparative incidence of detected violent crimes among cannabis users. One method has been to compile lists of violent crimes committed during specific periods of time and to determine the proportion of these offenses committed by cannabis users.

Lambo (1965) compiled a list of crimes occurring in three West African countries during a recent two-year period. He claimed that users of cannabis had committed 51% of the 73 murders, 31% of the 263 cases of assault and battery and 26% of the 472 cases against women.

Some have preferred to base their statistical studies on samples of offenders (rather than lists of offenses) drawn from the arrest or conviction files of law enforcement agencies. Several researchers adopting this method are content to identify the marihuana users in their samples and then simply report the number of users charged with violent crimes or the proportions of the total number of violent crimes perpetrated by the users.

The District Attorney of New Orleans, for example, testified before the House Ways and Means Committee that of the 450 men convicted of major crimes in 1930, 125 were identified as regular marihuana users. Approximately one-half of the murderers and one-fifth of those charged with assault, robbery or larceny were said to be regular marihuana users (U.S. House of Representatives, 1937: 23-24).

Bromberg (1939) reviewed the records of 16,854 offenders in the psychiatric clinic of New York County's Court of General Sessions during the period 1932 to 1937. Of the 67 marihuana users identified, only six had been charged with violent crimes. He concluded that there was no causal relationship between marihuana use and aggressive crime.

Others go one step further and attempt to compare the users' rates of violence with those of other selected populations such as non-marihuana using offenders, offenders using other drugs, or all of fenders in a given file.

Bromberg and Rodgers (1946) studied the civilian and military criminal records of 8,280 convicted offenders at the United States Naval Prison in Portsmouth, Now Hampshire between January 1, 1943 and July 1, 1945. Of the total number of offenders investigated, 40 or .0048% were identified as marihuana users (23 used to excess, 10 were moderate users and seven were described as light users). Of these 40, only two reported being more aggressive while under the influence of marihuana than they would be under normal conditions and three had been charged with violent crimes (assault or striking an officer) while in the military. Comparison of the users' criminal records with those of 40 randomly selected non-using prisoners revealed that the non-user group had committed more aggressive crimes than the users.

In conclusion, the researchers stated that:

  1. There is no positive relationship between aggressive crime and marihuana usage in the Naval service; . . .
  2. . . . there is no significant causal relationship between aggressive crime in civilian life (of the naval offenders studied) and the use of marihuana . . . .
  3. Marihuana usage is but an aspect of some type of mental disorder or personality abnormality (p. 826).

Maurer and Vogel (1962) have stated a similar conclusion.

"It has not been our impression from contact with many hundreds of marijuana users that these people are violent criminals; ... While there may be occasional violent psychopaths who have used marijuana, have committed crimes of violence, and who have, in court, explained their actions as uncontrolled violence resulting from the use of the drug, these are exceptions to the general run of marijuana users.... Marijuana is not possessed of any mysterious power to force people to commit acts which they would not otherwise perform (p. 281).

Blum (1969) reviewed the data provided in 1966 by the Federal Bureau of Investigation as part of its Careers in Crime Project. The data showed that marihuana users did not differ significantly from either heroin users or from all offenders (drug and non-drug users) in their rate of violent crime relative to their total non-drug offenses (28%, 26% and 26%, respectively).

There have been several statistical studies, also using offender populations, designed to assess the degree to which persons arrested for cannabis use have previous or subsequent arrests for violent crimes.

Bromberg and Rodgers (1946) found that of the 40 offenders in their sample identified as marihuana users, 12 had been charged with previous offenses, three of them for assault.

Gardikas (1950) reviewed the criminal records of 379 persons arrested between 1919 and 1950 for publicly using hashish. Of these, 117 (31%) reportedly progressed from hashish use to other crimes, about one-third of these subsequent crimes involving violence or weapons. Gardikas stated that one subgroup of these, offenders accumulated 420 offenses of assault, woundings, threats, robberies, and manslaughter (p. 5).

In sum, these statistical studies based on samples of violent offenses, violent offenders or arrested marihuana law violators indicate that some individuals identified as marihuana users do commit violent crimes, have committed them in the past and go on to commit them in the future.

Their numbers, however, are generally small, both absolutely and relatively. These studies therefore suggest a very weak and insignificant statistical association between marihuana use and violent crime which may itself be completely attenuated when the proper statistical controls are applied.

These studies do not establish a causal relationship between cannabis use and violent crime; nor do they permit an affirmative response to the crucial question of whether the use of marihuana alters the progression to violent crime at a significantly greater rate than that which might be expected from some other criminal subgroups, more representative samples of cannabis users, or samples drawn from the general population. They also fail to address themselves to the external conditions and circumstances which might serve to mitigate the observed relationships.

Several recent and more sophisticated empirical investigations have addressed some of the critical questions left unanswered by statistical studies of offender populations. Namely, they set about to determine whether marihuana users in the general population commit acts of aggression or violence significantly more frequently than do nonusers; and whether any observed differences between users and non-users may be more directly attributable to extra-pharmacological (social, cultural, psychological) variables than to the use of marihuana itself or to the pharmacological action of the drug per se.

In 1965, Robins and his associates (1970) conducted a survey of 20 black men born in St. Louis between 1930 and 1934. The marihuana users in the sample were then compared with the nonusers relative to their ratings on a "violence syndrome" constructed by the researchers.

Respondents were rated high on the violence syndrome if they reported having participated or felt like participating in three or more of the following items, one of which was a judgment by the interviewer that the respondent demonstrated hostility during the interview:

1. Getting hurt in a fight.

2. Ever feeling like killing someone.

3. Ever hitting people when angry.

4. Being quick to lose one's temper.

5. Throwing or breaking things when angry.

6. Ever hurting someone in a fight.

7. Ever fighting with a weapon.

8. Getting mean when drinking.

9. Interviewer's observation of respondent's hostility.

The researchers found that those who had used marihuana during adolescence were more likely to score high on the violence syndrome than were those who did not use the drug for the first time until adulthood; 31% of the respondents who had used marihuana and no other drug during adolescence exhibited three or more of these measures, 24% of those who used marihuana only but started as adults scored high, 16% of the non-users were classified as high on the violence syndrome, and 45% of those who used marihuana and other drugs were so classified.

The researchers also found that users were significantly more likely to report the, commission of " adult person or property offenses" than were nonusers; 32 % of the nonusers, 48 % of the marihuana only adult starters, 56% of the marihuana only adolescent starters, and 77% of the multiple drug users reported committing crimes against persons or property as adults.

Based on these data, marihuana users were said to be significantly more likely to have exhibited violent behavior than were nonusers. This conclusion, however, seems somewhat premature.

First, upon the application of three "pathological" controls (dropping out of school, alcoholism and involvement in juvenile delinquency), the original relationship was reduced to some unspecified extent; the researchers reported only that these controls "failed to completely wipe out" the statistical correlation. Secondly, several of the items would not appear to be sufficiently discriminating in that large numbers of people, whether drug users or not, have probably been quick to lose their temper, hit people when angry (most parents, for example), or felt like killing someone in a moment of anger. The subjective nature of the last item the interviewer's observation of hostility has already been noted.

Thirdly, neither the drinkers nor those who were multiple drug users were isolated in the analysis, making it impossible to determine whether or not the apparent relationship between marihuana use and violence may have been a. function of these other drugs rather than the marihuana.

Lastly, but perhaps most importantly, the researchers found several other "pathological" variables correlated with the use of marihuana in their sample: (a) low income, (b) low status jobs, (c) unemployment, (d) receiving financial aid, (e) failing to graduate from high school, (f) fathering illegitimate children, (g) marrying women who had been married previously or who had children, and (h) drinking "heavily enough to create, social or medical problems."

Because none of these variables was controlled in the data analysis (despite the fact that most of them have been found to be significantly related to delinquency and crime and characteristic of persons involved in delinquent, criminal and drug subcultures), it is impossible to determine whether or not any or all of these variables played a mediating role in the observed relationship between marihuana use and antisocial behavior in the, sample. As Goode (1972) has noted, the fact that the three controls which were applied did reduce the relationship, makes it likely that "additional controls would reduce the relationship even more, indeed, reduce it to zero, if applied simultaneously" (p. 13).

As such, although this study represented a significant step forward in investigating the relationship between marihuana and crime or violent behavior, its methodological limitations preclude generalizations of the findings to the larger universe.

In a study of drug use among lower class minority group youth, Blumer and his associates (1967) found that marihuana users were much less likely to commit aggressive or violent acts than were those who used amphetamines or preferred alcohol, and that most of the marihuana using youths deliberately shunned aggressive behavior and adopted, instead, a "cool," non-violent style. The researchers did find a small group of youths (termed "the rowdy") who were oriented toward aggressiveness. Generally, these youths preferred alcohol over other drugs and were found, for the most part, to have been raised in an aggressive and combative social milieu. The researchers point out, however, that most marihuana users in the sample were not of the rowdy type, even though it is this small group which often forms the basis of the public and police image of the youthful marihuana user. In commenting on the role of marihuana in the passage of youth from rowdy to a cool style, the authors note, that the passage from the rowdy type to a cool and mellow youngster, as it relates to the use of drugs, involves chiefly a shift to the smoking of marijuana. . . . [The youngsters'] accounts and discussions also stress that the use of marijuana both produces and symbolizes a "mellow" mode of conduct that is opposed to that associated with rowdy behavior. They place great weight on the "socializing" effects of marijuana use, declaring that its use not only leads youngsters away from violence but has the effect of changing them into social human beings (p. 30).

In a large scale, systematic survey (questionnaire and interview) of more than 1300 students at five West Coast colleges and universities, Blum and his associates (1969) found that 19% of the total sample had used marihuana but that 94% had used alcohol. One, percent of the marihuana users reported fights or other criminal behavior which they attributed to the drug. Of those who used alcohol, 8% reported fights and 2% reported offenses while under the influence of this drug. The researchers make particular note of the fact that despite the increase of marihuana use on these campuses since the middle and late sixties, there has been no comparable increase in assaultive crimes.

In a Commission-sponsored household survey of 15 to 34 year-old male residents of West Philadelphia, Goode (1972) found that not one of the violent crimes, including "forcing sexual intercourse," was significantly correlated with marihuana use. Among the five offense types showing a very weak relationship to the use of marihuana, the only so-called violent offense, "hurting someone in a minor way," showed the weakest association. The author notes that "the statistical differences in rates of offenses between users and nonusers rest on adding together a small number of weakly correlated offenses. . . . [They do not indicate] massive differences, or differences indicating higher rates of classic, violent crimes among users" (p. 32a).

These more rigorous studies of the relationship between marihuana use and violent crime suggest that marihuana users in the general population do not commit acts of aggression or violence significantly more frequently than do nonusers; that marihuana does not heighten aggressive tendencies in most users and may, in some cases, serve to reduce aggressiveness; and that much of the observed relationship between marihuana and violence is probably a function of social, cultural or psychological variables such as multiple drug use, set and setting and involvement in a criminal or drug subculture.

There is no reason to believe that marihuana use will cause or lead to the commission of aggressive or violent acts by the large majority of psychologically and socially mature individuals in the general population.


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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Marihuana, A Signal of Misunderstanding