By Christopher Ingraham

The Washington Post

How is legalization affecting car crash rates? It’s hard to tell

Last week, a pair of studies came to seemingly opposite conclusions on whether rising marijuana use is causing an increase in car crashes in states that have legalized the drug.

The first, conducted by the Insurance Institute for Highway Safety, analyzed insurance claims for vehicle collisions filed between January 2012 and October 2016. The IIHS researchers compared claims in states that had recently legalized marijuana — Colorado, Washington and Oregon — with claims in similar neighboring states that hadn’t.

They found that over that time period, collisions claim frequencies in the states that had legalized marijuana were about 3 percent higher than would have been anticipated without legalization. The researchers characterized that number as small, but significant. Collision claim frequency refers to the number of claims filed divided by the number of insured vehicle years.

“The combined-state analysis shows that the first three states to legalize recreational marijuana have experienced more crashes,” said Matt Moore, senior vice president of the IIHS’ Highway Loss Data Institute, in a statement.

But hot on the heels of that analysis came a second study, published in the American Journal of Public Health, that found no increase in vehicle crash fatalities in Colorado and Washington, relative to similar states, after legalization.

The authors of that study analyzed federal data on fatal car crashes from 2009 to 2015. “We found no significant association between recreational marijuana legalization in Washington and Colorado and subsequent changes in motor vehicle crash fatality rates in the first 3 years after recreational marijuana legalization,” they concluded.

On the one hand, a finding that legalization led to a small but significant increase in crashes. On the other, a study concluding that legalization had no effect on fatal crashes at all. Do the two contradict each other?

Not necessarily. The studies measured slightly different things: IIHS looked at claims for motor vehicle collisions, while the AJPH report focused more specifically on fatal crashes. It seems plausible that legalization could lead to a slight increase in minor accidents that don’t prove fatal.

Indeed, federal research has shown that while smoking weed before driving does indeed elevate your risk of a crash, it’s nonetheless far less impairing than alcohol, which dramatically increases the likelihood of a crash even at small doses.

In the end, it’s hardly surprising that choosing different comparison states will yield slightly different results on similar measures.

Any increase in car crashes is cause for concern. But on balance, public health experts worry more about fatal crashes than nonfatal ones, for obvious reasons. The AJPH study is heartening news on that front, and it comes on the heels of previous research showing that medical marijuana laws are also not associated with increased vehicle fatalities, and may in fact lead to fewer traffic deaths.

— The Washington Post

Drug-policy experts often say the health risks of marijuana use are relatively minor compared to the steep costs of marijuana enforcement: expensive policing, disrupted lives, violence and even death.

Law enforcement agencies, however, have often been at the forefront of opposition to marijuana legalization. One reason is the drug, with its pungent, long-lasting aroma, is relatively easy to detect in the course of a traffic stop or other routine interaction. It’s an ideal pretext for initiating a search that otherwise wouldn’t be justified — even if that search only turns up evidence of marijuana use and nothing more.

New data on traffic stops in Colorado and Washington underscore this point: After the states legalized pot, traffic searches declined sharply across the board. That’s according to the Open Policing Project at Stanford University, which has been analyzing public data of over 100 million traffic stops and searches since 2015.

“After marijuana use was legalized, Colorado and Washington saw dramatic drops in (police) search rates,” the study’s authors explain. “That’s because many searches are drug-related. Take away marijuana as a crime and searches go down.”

In Colorado and Washington, traffic searches of black, Hispanic and white drivers fell significantly after legalization, according to the Open Policing Project’s analysis. That pattern didn’t hold for states where marijuana use remained illegal.

The project’s data encompasses traffic searches initiated for any reason but excludes searches following an arrest. This makes the data a good barometer of searches initiated at an officer’s discretion. The numbers changed dramatically after legalization suggesting, as the researches do, that suspected marijuana use is often a factor in these searches.

Data also shows legalization didn’t eliminate racial disparities in the searches. Black and Hispanic motorists are still searched at considerably higher rates than white motorists. But following legalization, they are searched less often than they were before.

In 2014 a Washington Post investigation detailed how highway police often use suspicion of marijuana as justification to search drivers’ vehicles and ultimately seize cash and property from them, regardless of whether any drugs are ultimately found. From 2002 to 2012, the federal government seized roughly $1 billion in cash and other assets related to marijuana cases, according to the Wall Street Journal.

That figure doesn’t include seizures made by state and local law enforcement authorities who handle most of the nation’s drug enforcement.

If legalization leads to fewer searches, that means fewer seizures of cash and property, which could have a significant negative impact on the finances of police departments that have come to rely on those seizures to pad their budgets.

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