People who get drunk at parties don't always stay there until they sober up, people that get high at parties don't always stay they until they come down from it. I've had to have full out fights with friends who were high / drunk so many times to let me drive them home.
“For each of 2,500 injured drivers presenting to a hospital, a blood sample was collected for later analysis.
There was a clear relationship between alcohol and culpability. … In contrast, there was no significant increase in culpability for cannabinoids alone. While a relatively large number of injured drivers tested positive for cannabinoids, culpability rates were no higher than those for the drug free group. This is consistent with other findings.”
Source: Logan, M.C., Hunter, C.E., Lokan, R.J., White, J.M., & White, M.A. (2000).
The Prevalence of Alcohol, Cannabinoids, Benzodiazepines and Stimulants Amongst Injured Drivers and Their Role in Driver Culpability: Part II: The Relationship Between Drug Prevalence and Drug Concentration, and Driver Culpability. Accident Analysis and Prevention, 32, 623-32.
ON-ROAD PERFORMANCE STUDIES
“Marijuana's effects on actual driving performance were assessed in a series of three studies wherein dose-effect relationships were measured in actual driving situations that progressively approached reality.
… THC's effects on road-tracking after doses up to 300 µg/kg never exceeded alcohol's at bacs of 0.08%; and, were in no way unusual compared to many medicinal drugs. Yet, THC's effects differ qualitatively from many other drugs, especially alcohol. Evidence from the present and previous studies strongly suggests that alcohol encourages risky driving whereas THC encourages greater caution, at least in experiments. Another way THC seems to differ qualitatively from many other drugs is that the formers users seem better able to compensate for its adverse effects while driving under the influence.”
Source:
http://www.druglibrary.org/schaffer/Misc/driving/s1p2.htm[M]arijuana's slight impairment on psychomotor skills generally falls within the range of safety Americans accept for prescription medications and other legal, potentially debilitating factors such as fatigue or cell phones.
Source:
http://norml.org/index.cfm?Group_ID=5450#CrashLeave your high friends alone.