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Medical Marijuana Laws, Traffic Fatalities, And Alcohol Consumption


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Some of the pointed bits of info from this study.


Laboratory studies have shown that cannabis use impairs driving-related functions such

as distance perception, reaction time, and hand-eye coordination (Kelly et al. 2004; Sewell et al.

2009). However, neither simulator nor driving-course studies provide consistent evidence that

these impairments to driving-related functions lead to an increased risk of collision (Kelly et al.

2004; Sewell et al. 2009). Drivers under the influence of marijuana reduce their velocity, avoid

risky maneuvers, and increase their “following distances,” suggesting compensatory behavior

(Kelly et al. 2004; Sewell et al. 2009). In addition, there appears to be an important learning-bydoing component to driving under the influence of marijuana: experienced users show

substantially less functional impairment than infrequent users (Sutton 1983)



Like marijuana, alcohol impairs driving-related functions such as reaction time and handeye coordination (Kelly et al. 2004; Sewell et al. 2009). Moreover, there is unequivocal

evidence from simulator and driving-course studies that alcohol consumption leads to an

increased risk of collision (Kelly et al. 2004; Sewell et al. 2009). Even at low doses, drivers

under the influence of alcohol tend to underestimate the degree to which they are impaired

(MacDonald et al. 2008; Marczinski et al. 2008; Robbe and O’Hanlon 1993; Sewell et al. 2009),

drive at faster speeds, and take more risks (Burian et al. 2002; Ronen et al. 2008; Sewell et al.

2009). When used in conjunction with marijuana, alcohol appears to have an “additive or even

multiplicative” effect on driving-related functions (Sewell et al. 2009, p. 186), although there is

evidence that chronic marijuana users are less impaired by alcohol than infrequent users (Jones

and Stone 1970; Marks and MacAvoy 1989; Wright and Terry 2002).


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Good stuff Timmahh! I agree from personal experience with both alcohol and marijuana, that alcohol is way more impairing - like the quote said the more one drinks, the more one feels they are okay to drive, (and something the study didn't say but I think) also alcohol makes a person get more argumentative about how okay they are to drive & want to "Prove it".


I'd be happy to volunteer for a study on how well people drive on mj :D

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