Schaffer Library of Drug Policy

Marihuana: A Signal of Misunderstanding

Marihuana and Driving

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
Previous Page Next Page

The Report of the National Commission on Marihuana and Drug Abuse

Marihuana and Driving


The United States Department of Transportation has estimated that in 1970, more than 111 million Americans were licensed drivers and that there were approximately 109 million vehicles registered and regularly traversing America's streets and highways. The Commission-sponsored National Survey (Abelson, et al., 1972) has revealed that approximately 21 million or 15% of all American adults 18 years and over have tried marihuana and that about 6.9 million adults currently use the drug.

At the present time, there is no reliable estimate of the proportion of marihuana users who drive while "high," but America's tragic experience with highway accidents and fatalities involving persons driving under the influence of alcohol raises serious questions about the extent to which marihuana impairs driving skills and performance and thereby constitutes a public safety hazard on this nation's thoroughfares.

In recent years, public safety experts, along with the medical and scientific communities, have devoted increasing attention to the effects of any mind-altering drug on driving, but there is as yet little evidence to inform discussion. As part of its more general concern with the impact of marihuana on public safety, the Commission has reviewed the available research and has concluded that the evidence which presently exists is, at best, inconclusive.

In view of this finding and prior to a rather brief summary of the knowledge we now have, the Commission feels compelled to urge the public to consider these findings as only tentative, to adopt an extremely cautious attitude about the effects of marihuana on driving skill and performance, and perhaps most importantly, to avoid driving at all while under the influence of any mind-altering drug or intoxicant.

Previous Page Next Page