The government’s review of the 1995 marijuana rescheduling petition did not distinguish between use and abuse according to professional standards, such as those in use by the medical and scientific community. Widespread use of cannabis is not an indication of its abuse potential, and widespread use of marijuana without dependency supports the argument that marijuana is safe for use under medical supervision.

Since marijuana, heroin and other drugs are often referred to as “drugs of abuse", many consider each use of these drugs “abuse”. That a clear differentiation between the two terms if often lacking is suggested by Wish (1990), who noted in an editorial of the Journal of the American Medical Association on drug screenings in the workplace that a discussion on the difference between drug use and drug abuse was often regarded as "anachronistic and unpatriotic."

However, the term "substance abuse" is clearly defined and should be differed from simple and unproblematic use, which is the rule and not the exception with most drugs, even in adolescents. Scientists usually differentiate between use, and forms of problematic use. The most frequent terms for problematic or pathological use are abuse, misuse, harmful use and dependency (e.g. Gorman and Derzon 2002, Swift et al. 2001). Definitions for these terms vary so that samples determined using different definitions overlap. Swift et al. (2001) compared dependency according to the DSM-IV (Diagnostic Manual of Diseases) to the concept of dependency in the ICD-10 (The International Classification of Diseases, 10th Revision) in a sample of 10,641 representative Australian adults:

The prevalence of DSM-IV (1.5%) and ICD-10 (1.7%) cannabis dependence was similar. DSM-IV and ICD-10 dependence criteria comprised unidimensional syndromes. The most common symptoms among dependent and non-dependent users were difficulties with controlling use and withdrawal, although there were marked differences in symptom prevalence. Dependent users reported a median of four symptoms. There was good to excellent diagnostic concordance (kappas = 0.7-0.9) between systems for dependence but not for abuse/harmful use (Y = 0.4). These findings provide some support for the validity of cannabis dependence.

According to the newer DSM-IV definition cannabis abuse and dependency will be observed more often than according to the criteria of the earlier DSM-III-R:

"We assessed a clinical sample of 102 adolescents using CIDI-SAM. Prevalence of either an abuse or dependence diagnosis was lower with DSM-IV than DSM-III-R except for cannabis and alcohol, and concordance rates were better for dependence than for abuse. For most substances, rates of DSM-IV withdrawal were lower than in DSM-III-R, but rates of DSM-IV physiological dependence remained high. Changes in DSM-IV criteria appear to have impacted diagnoses in these adolescents, particularly for the substances they use most--i.e. alcohol, tobacco, and cannabis" (Mikulich et al. 2001).

Clinical criteria for substance abuse according to DSM-IV are:

A. A maladaptive pattern of substance use leading to clinically significant impairment or distress, as manifested by one or more of the following occurring within a twelve-month period.

(1) Recurrent substance use resulting in a failure to fulfill major role obligations at work, school, or home (e.g. repeated absences or poor work performance related to substance use, substance related absences, suspension, or expulsions from school; neglect of children or household).

(2) Recurrent substance use in situations in which it is physically hazardous (e.g. driving an automobile or operating a machine when impaired by substance use).

(3) Recurrent substance related legal problems (e.g. arrest for substance related disorder conduct).

(4) Continued substance use despite having persistent or recurrent social or interpersonal problems caused or exacerbated by effects of substance (e.g. arguments with spouse about consequences of intoxication, physical fights).

B. Symptoms have never met the criteria for substance dependence for this class of substance.

When talking about the gateway theory, the Institute of Medicine (1999) pointed out that it is necessary to differentiate between use and dependency or abuse to draw the right conclusions from given data:

"Many of the data on which the gateway theory is based do not measure dependence; instead, they measure use -even once- only use. Thus, they show only that marijuana users are more likely to use other illicit drugs (even if only once) than are people who never use marijuana, not that they become dependent or even frequent users. The authors of these studies are careful to point out that their data should not be used as evidence of an inexorable causal progression; rather they note that identifying stage-based user groups makes it possible to identify the specific risk factors that predict movement from one stage of drug use to the next -the real issue in the gateway discussion" (Joy et al. 1999).

Modern epidemiological studies have shown that many people who use cannabis do not differ from other people, that they do not abuse the drug but use it. A survey of 15,000 British children aged 14 and 15 found that young people with high self-esteem are more likely to take illicit drugs than those whose self-confidence is low (Observer of 11 February 2001). The results contradict the concept that drug use is most prevalent among anxious or insecure youth looking for an escape from poor conditions or a way to feel better about themselves. Heather Ashton, a professor of pharmacology at Newcastle University, said that the results of the survey did not surprise her: "Students all report they take drugs for pleasure and that it has nothing to do with anxiety or stress. Years ago young people who take drugs were seen as psychotic or low risk-takers. Now that is not the case."

A report published by the Institute of Medicine provides an equally clear assessment of contemporary scientific standards for defining drug use, abuse, and dependency. The report "Pathways of Addiction, Opportunities in Drug Abuse Research" was published in 1996. According to its introduction:
"The report employs the standard three-stage conceptualization of drug-taking behavior that applies to all psychoactive drugs, whether licit of illicit. Each stage -- use, abuse, dependence -- is marked by higher levels of use and increasing serious consequences. Thus, when the report refers to the "use" of drugs, the term is usually employed in a narrow sense to distinguish it from intensified patterns of use. Conversely, the term "abuse" is used to refer to any harmful use, irrespective of whether the behavior constitutes a "disorder" in the DSM-IV diagnostic nomenclature. . . . It bears emphasizing that adverse consequences can be associated with patterns of drug use that do not amount to abuse or dependence in a clinical sense, although the focus of this report and the committee's recommendations is on the more intensified patterns of use (i.e, abuse and dependence) since they cause the majority of serious consequences." (Committee on Opportunities in Drug Abuse Research, 1996)

The findings above clarify marijuana’s abuse potential relative to other drugs; the use of more dangerous drugs is not a significant risk for most individuals whose consumption of marijuana can be described as use rather than abuse or dependence. These findings affirm that medical users of marijuana are not at risk to use of other illicit drugs due to their regular use of cannabis.

The College on the Problems on Drug Dependence recognizes that marijuana is not a harmless drug, but they note a basis for distinguishing marijuana from drugs such as cocaine and heroin. They also note that serious questions have been raised as to whether marijuana is sufficiently dangerous to justify criminal sanctions, and are critical of DEA’s irrational scheduling decisions with respect to marijuana:
"Despite these significant adverse effects, questions have been raised by various investigative commissions about whether the social costs associated with the prohibition of marijuana are warranted by its actual harm to individuals and society, and especially whether imprisonment for mere possession unaccompanied by other crimes -- the law in some states -- is appropriate. It can be argued that placing marijuana in the same category as heroin and cocaine also sends a counterproductive message because it erases distinctions among drugs with very different degrees of hazard." (College on the Problems of Drug Dependence, 1997).

Gorman (2002) uses data from several prospective longitudinal studies (N= 3206) to examine the association between three psychological constructs on the use, misuse, and abuse of marijuana – providing an example of research and analytical strategies that incorporate the distinctions discussed above. Many drug users not only do not move on to more dangerous drugs, many of them also stop using drugs on their own as they age.

“[This research] examined patterns of illicit drug use, abuse, and remission over a 25-year period and recent treatment use. . . .[utilizing] Retrospectively obtained year-to-year measures from the 1996-1997 survey included use and remission of sedatives, stimulants, marijuana, cocaine, and opiates, as well as substance abuse and psychiatric treatment use. . . . Most drug abusers who had started using drugs by their early 20s appeared to gradually achieve remission. Spontaneous remission was the rule rather than the exception. Nonetheless, considerable unmet needs existed for those who had continued use into middle age.” (Price et al, 2001).

References

College on the Problems of Drug Dependence, Statement on National Drug Policy, March 1997
Committee on Opportunities in Drug Abuse Research, Institute of Medicine. National Academy Press. Washington, D.C. 1996.
Gorman DM, Derzon JH. Behavioral traits and marijuana use and abuse: a meta-analysis of longitudinal studies. Addict Behav 2002;27(2):193-206
Mikulich SK, Hall SK, Whitmore EA, Crowley TJ. Concordance between DSM-III-R and DSM-IV diagnoses of substance use disorders in adolescents. Drug Alcohol Depend 2001;61(3):237-48
Price RK, Risk NK, Spitznagel EL Remission from drug abuse over a 25-year period: patterns of remission and treatment use. Am J Public Health 2001 Jul;91(7):1107-13
Swift W, Hall W, Teesson M. Characteristics of DSM-IV and ICD-10 cannabis dependence among Australian adults: results from the National Survey of Mental Health and Wellbeing. Drug Alcohol Depend 2001;63(2):147-53.
Wish ED. Preemployment drug screening. JAMA 1990;264(20):2676-2677.