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Major Studies of Drugs and Drug Policy
Marihuana, A Signal of Misunderstanding - Table of Contents

The Report of the National Commission on Marihuana and Drug Abuse

Marihuana and (Non-Violent) Crime


In this section, it is our job to explore two basic issues:

  1. Do marijuana users commit crimes and offenses any more frequently titan non-users do?
  2. Are any variables with which marijuana use is strongly related also correlated with criminality?

In the next section I will deal with a third question, and one which is probably the most crucial one in this report: Can the marijuana-crime connection be explained mainly by the use of marijuana in and of itself, or is use itself dependent on third variables which themselves explain the commission of offenses?

As the principal measure of committing crimes, this study has employed the number of different types of offenses admitted to in the 16 categories asked about. Naturally, there are many other crimes not asked about, and, in addition, some of these crimes would not correspond to the image most people would have of "classic" aggressive offenses-such as "disturbing people," or receiving stolen goods. However, as a general index or overall measure of criminality of different groups or categories of individuals, this one is as good as any others that have been employed, and is probably adequate for our purposes. (The survey, it must be noted, did not ask questions about any white collar crimes, which must be reckoned into an adequate measure of output of criminal behavior-but these crimes do not correspond with the public's image of aggressive crimes committed under the influence of marijuana, and so their absence is less relevant than would appear at first glance.) Throughout the remainder of this report, the number of crimes and offenses will be employed as the dependent variable-the outcome to be explained. And throughout, I will be examining the marijuana-crime connection-as well as other relationships-insofar as it bears on file basic issue.

Before the analysis proceeds, it should be pointed out that of the 16 offenses, not one of the violent crimes correlated with marijuana use in any meaningful way at all, and a very weak relationship was evidenced with only five of the offenses-stealing from a store, buying stolen property, disturbing people, damaging property, and hurting someone in a minor way (the last of which showing the weakest association of all). The statistical differences in rates of offenses between users and non-users rest on adding together a small number of weakly correlated offenses. When offense differences are discussed, the reader should not hold the mistaken impression that they indicate massive differences, or differences indicating a higher rate of classic, violent crimes among users. With that warning in mind, we may now proceed to user/non-user differences in offenses.

The first relationship to be presented, then, is whether marijuana users as a whole commit offenses any more frequently than non-users as a whole. The answer is yes. I have employed two indicators of marijuana use; one is frequency of marijuana use during the period of most recent use (which may have been in the past, or may be at present), and whether or not the respondent has ever, or has never, used marijuana. Both indicators of marijuana use correlate very powerfully with committing offenses. For both tables, the differences are significant beyond the .001 level, employing Chi-square as a test of significance, which means that the differences observed could occur at random only one chance in a thousand. This is considered extremely significant. There is a regular and step-wise relationship between frequency of use and committing offenses; the more that a given respondent smokes marijuana, the greater is the likelihood that lie will have committed four or more offenses, and the lower is his likelihood of committing no offenses at all. Over a third (38%) of those who have never smoked marijuana said that they committed none of the 16 offenses asked about-but this was true of only one respondent in eight (or 12%) of the regular smokers. At the other end, there was a 17% difference between non-users and regular users (24% vs. 41%) in admitting to four or more of these offenses. Tables 3 and 4 present these data in detail.

We would be remiss in our duties as sensitive and acute social analysts if we ended the analysis there. The simple correlation between marijuana use and offenses may very well mask important and even more basic relationships buried beneath it. Marijuana is correlated in a simple manner with the commission of crimes,, but does it remain correlated when controls are applied? In other words, is it a spurious relationship, or one which will remain when crucial variables are held constant' Which-factors are also related to the commission of offenses-which might actually themselves explain the simple marijuana-crime connection? There are several such variables-race, age, education, the use of other drugs, and the respondent's involvement in the drug subculture. Blacks are significantly less likely to use marijuana (64% of the blacks in the survey said that they had tried marijuana, but 86% of the whites said that they had done so), but slightly more likely to admit to the commission of offenses--41% of all blacks said that they committed four or more offenses but this was true of only 25 ) % of all whites (see Tables 23 and 25). Does the marijuana-crime correlation hold up for blacks and whites separately? Age was also related to both offenses and marijuana. The oldest respondents (age 29-34) were least likely to have tried marijuana (61%), the youngest (15-20) were next least (73%), and the intermediate age groups (21-23 and 24-28) were most likely to have tried marijuana (82% and 80%). There was a linear relationship between age and offenses, however. The youngest group was least likely to have committed no offenses (20%), and most likely to have committed four or more (42%) ; the oldest group was most likely to, have committed no offenses (35%), and least likely to have committed four or more (22%) (see Tables 29-31). Thus, we would want to know whether marijuana and crime still correlate in each age group separately. The same thing can be said for education (Tables 26-28), the use of drugs other than marijuana (Tables 11-16), and having friends who use drugs (Tables 17-22)-the relationship between marijuana use and crime could be mitigated or even transformed altogether if these third variables are considered. One possibility is that the marijuana-crime relationship is wiped out altogether with the application of these controls-that is, that the relationship is completely spurious. A second possibility is that the marijuana-crime connection may be specific to some groups or categories, but not others. And the third possibility is that the same original relationship remains basically unaltered, or even is strengthened, by the application of these controls.

Special attention ought to be paid to the drug-related variables. There is a powerful and significant association between the use of marijuana and the use of other drugs. Although recent studies have presented evidence that this basic relationship is probably not due to the effects of marijuana per se, but to friendships and associations made in conjunction with marihuana use . . . , the simple relationship between marihuana and other drugs is a statistical fact. There is, in addition, a strong and marked association with using drugs other than marijuana and the commission of crimes. Thus, a legitimate question to be explored is whether "marijuana only" users have a greater crime rate than non-users, whether the higher rate of the commission of offenses cannot be attributed largely or solely to using drugs other than marijuana.


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