Liberal marijuana laws have public officials questioning whether there will be changes (in the form of substantial increases) in the number of traffic related deaths that result from intoxicated driving. While proponents of marijuana legalization tend to lean towards a reduction in the number of traffic related deaths resulting from the legalization, opponents worry that the decision by lawmakers to legalize pot may pose critical risks to the public on the roads.
According to the University of Washington, three different groups of studies have been performed to examine the relationship between marijuana use and the effects on an individual's ability to operate a motor vehicle. These studies include:
- Laboratory studies which detected impairments which would directly affect a user's ability to properly operate a motor vehicle.
- Driving simulator studies which "suggested that marijuana use acts in a dose-dependent manner to reduce drivers' average speed, and increase their lane position and steering wheel variability and reaction times."
- Field studies which "found that although crash culpability was not elevated for low concentrations of THC, risk of involvement in a traffic crash increased as drivers' THC levels increased, and became significantly (up to 6.6 times) greater than that for drug free drivers, at higher concentrations of THC."
According to Jonathan Adkins, director of Governors Highway Safety Association, "We don't know enough about the scope of marijuana-impaired driving to call it a big or small problem. But anytime a driver has their ability impaired, it is a problem."
Researchers in 8 out of 9 studies found that marijuana use was directly related to the risk of vehicular crash. Drivers who test positive for marijuana are more than 2 times as likely to be involved in a motor vehicle accident. Unfortunately, these studies were inconclusive in determining whether users were high on marijuana at the time of their accidents, as Highway Patrol testing only checks for the presence of THC in the user rather than testing from an actual level of THC.
Columbia University researchers found that the use of marijuana alone increased the chances of fatal accident by 80% over those who were not the subject of any type of substance impairment. The use of marijuana and alcohol further escalates problems resulting in:
- Slower Decision Making
- Reduction in Peripheral Vision
- Inability to Multitask
- Increased Driving Impairment