While stopping short of directly blaming legal weed for a noticeable increase in impaired driving car crashes, the study says there's enough of a correlation to cause them to believe pot is a factor. Before you go off disputing, consider this study came from the respected Highway Loss Data Institute (HLDI).

According to US News And World Report, the HLDI found a 2.7 percent increase in collision claims in WA and Colorado compared to pre-legal pot dates, and compared with surrounding states where weed is still illegal.

The HLDI says they cannot 100% directly point to weed as the cause, because there isn't a marijuana field sobriety test yet that can (like alcohol) prove on the spot the driver is impaired. But there's enough evidence to strongly suggest pot impaired driving has risen in states where marijuana is legal.

According to US News, the Senior VP of the HLDI, Matt Moore said:

"We're concerned about what we're seeing. We see strong evidence of an increased crash risk in states that have approved recreational marijuana sales."

Accident claims in Washington, Colorado and Oregon, among other states, were closely monitored after marijuana was legalized in WA and CO.  Officials say after a steady decline in claims,  Colorado climbed 16 percent, and Washington 6.2 percent between 2012 and 2016. This, plus other data, led the HLDI to say they believe pot is responsible.