A second hypothesis reflecting the statements of significant numbers of government officials is that marihuana plays a major role in the commission of other, essentially non-violent, forms of criminal and delinquent behavior.

In general, those espousing this more general cause-effect relationship assume that the drug frequently produces, in addition to the lowering of inhibitions, impairment of judgment, distortion of reality and at least temporary reduction of a sense of personal and social responsibility. Indeed, the earlier stereotype of the marihuana user was that of an immoral, physically debilitated, psychologically unstable and criminally marginal man whose state of severely and irreversibly underdeveloped psychosocial and moral maturity was said to derive directly from his continued use of marihuana.

As indicated earlier, neither the inherent complexities of the issue nor the previously inconclusive empirical evidence has deterred the formulation and expression of strong opinions about the relationship of marihuana use to crime and delinquency. Opinion in this area, quite apart from the empirical evidence, has long assumed critical importance in the development of social policy.

The Commission has addressed the issue in three different ways. One was to assess the state of current public and professional opinion relative to the general proposition that marihuana causes or leads to the commission of criminal or delinquent acts. A second approach was to review the professional literature addressed to the issue, and a third was to initiate empirical investigations of our own.

The opinion surveys found that substantial numbers of persons raised serious questions about the existence of a causal relationship between marihuana use and criminal or delinquent behavior. Confusion and uncertainty about the existence of such a relationship have been expressed by both youth and adults, including practicing professionals in the criminal justice system.

Recent data suggest that some of this confusion may be the result of a fairly widespread misconception about the addiction potential of marihuana. To the extent that persons believe marihuana users are physically dependent on the -drug, they may assume that, like the heroin user, the marihuana user commits his offenses in order to support what is perceived as a drug habit; and that, like the heroin model, offenses are committed more often in the desperate attempt to obtain the drug rather than under its influence following use. There is no evidence that this is the case, even for those who use the drug heavily.

In the Commission-sponsored National Survey, the respondents were asked whether they agreed or disagreed with the statement that "many crimes are committed by persons who are under the influence of marihuana." Fifty-six percent of the adult population and 41% of the youth indicated agreement. As in the Survey generally, there was a significant difference of opinion according to age in the adult population. While 69% of the over-50 age group agreed with this statement, only about one-third of the 18-to-25 age group and the 14-to-17-yearolds agreed. One of every four youth respondents and 18% of the adults said they were "not sure" of the existence of such a relationship between marihuana use and crime.

Much greater consensus exists, even between generations, regarding the association of alcohol and crime. While 56% of all adults expressed their belief that many crimes are committed by persons under the influence of marihuana, 69% of these same adults believed that alcohol was related in the same way. Only 7% felt unsure about the alcohol crime relationship, in contrast to 18% who expressed uncertainty about the relationship between crime and marihuana.

The Commission also surveyed opinion within the criminal justice community. A sample of 781 judges, probation officers and court clinicians replied to a questionnaire which asked respondents to indicate whether or not their professional experience led them to believe that "use of marihuana causes or leads to antisocial behavior in the sense that it leads one to commit other criminal or delinquent acts." Of all respondents, 27% believed this to be the case. Within each professional group, 34% of the judges, 18% of the probation officers and 2% of the clinicians indicated their agreement.

On the assumption that some, proportion, however small, of marihuana users might ultimately be arrested for non-drug offenses, these officials were also asked to assess the relative, truth of the statement that "most non-drug offenses committed by persons who are known users of marihuana or are found to have marihuana on their person or in their possession occur when the offender is under the influence of marihuana." Seventy-one percent of the responding judges, 75% of the probation officers and 85% of the court clinicians either thought the statement false or were unsure of its accuracy.

Respondents likewise rejected, however, the proposition that these crimes perpetrated by marihuana users occur when the offender is attempting to obtain the drug rather than while under its influence; 65.6% of the judges, 64.6% of the probation officers and 78.3% of the court clinicians either denied or were unsure of the truth of this proposition.

In short, marihuana, is not generally viewed by participants in the criminal justice community as a major contributing influence in the commission of delinquent or criminal acts.

This increasing professional skepticism is buttressed by the weight of research findings. A comprehensive review of the literature revealed that in the various offender populations studied for this purpose, only a small percentage were marihuana users. In only a handful of cases did researchers report that criminal conduct followed the use of marihuana. Generally, the rate of self -reported, non-drug crime did not significantly differ between users and non-users.

Both of the Commission-sponsored studies (the New York and Philadelphia studies referred to earlier) corroborated this research consensus. In the Philadelphia study, for example, less than 10% of the sample were known to the police, and there were no significant differences among marihuana users and non-users in the sample who reported the commission of major criminal acts when statistical controls were applied. Further, most of the first offenses committed by users occurred prior to their use of marihuana, and only in rare instances did the offenses immediately follow (within 24 hours) upon the use of marihuana (five cases out of 741 first offenses and 19 cases out of 516 most recent offenses).

Likewise, the New York study revealed that about one-fifth of -the marihuana law violators arrested between 1965 and 1969 were found to have previous arrest records. Of those with previous arrests, the great majority of offenses (86%) involved traffic violations and minor violations of the vagrancy statutes. In but 10% of the cases the previous arrests were for assault, robbery, burglary or larceny.

In essence, neither informed current professional opinion nor empirical research, ranging from the 1930's to the present, has produced systematic evidence to support the thesis that marihuana use, by itself, either invariably or generally leads to or causes crime, including acts of violence,, juvenile delinquency or aggressive behavior. Instead the evidence suggests that sociolegal and cultural variable's account for the apparent statistical correlation between marihuana use and crime or delinquency.