Researchers are divided on the issue of whether or not marijuana use leads to more traffic accidents.

Montana, Washington State and Colorado have limited marijuana intoxication to five parts per billion in a designated driver's blood. Although most states don't have a specific level for marijuana intoxication, many are currently making moves to set thresholds.

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Safety advocates are worried the drug can reduce decision-making abilities and make multitasking difficult. Peripheral vision, which is also a must-have skill when driving, is also affected when a person consumes weed.

Some believe while alcohol causes drivers to be reckless, driving faster than normal, drivers under the influence of marijuana tend to drive slower.

Some point out that can be even more cautious than sober drivers, with more room between them and other vehicles. They have also been known to allow other cars to pass them on the road.

Drivers that have consumed marijuana are said to be more aware of their impairment than alcohol drinkers, so they are more cautious on the road.

Researchers do agree that combining alcohol and marijuana causes much greater impairment than taking either one of the substances alone.

Law makers and police are currently discussing how to handle drivers who use the drug.

"We don't know enough about the scope of marijuana-impaired driving to call it a big or small problem. But anytime a driver has their ability impaired, it is a problem," said Jonathan Adkins, executive director of Governors Highway Safety Association.

Testing for cannabis is also tricky. The effects of the drug can be experienced for just a few hours, but the drug can be detected in the body days or even weeks after it was ingested.

The number of marijuana users that drive in Washington State rose by 25 percent in 2013. There was no increase in traffic accidents in the state during the same time.