«States that legalize medical marijuana see fewer fatal car accidents, according to a new study, in part because people may be substituting marijuana smoking for drinking alcohol.
Sixteen states and the District of Columbia, have legalized medical marijuana since the mid-1990s. For the new study, economists looked at 1990-2009 government data on marijuana use and traffic deaths in the 13 states that had passed legalization laws during that time period. The data were from the National Household Survey on Drug Use and Health and the National Highway Traffic Safety Administration.
Comparing traffic deaths over time in states with and without medical marijuana law changes, the researchers found that fatal car wrecks dropped by 9% in states that legalized medical use — which was largely attributable to a decline in drunk driving. The researchers controlled for other factors like changes in driving laws and the number of miles driven that could affect the results.»