As the number of states legalizing recreational and medical marijuana continues to grow questions are being raised regarding whether or not this legalization will equate to more drivers getting behind the wheel stoned.

So far, not a lot is known about whether or not more people are driving high in these states, nor is much known about how driving under the influence of marijuana will contribute to accidents or fatalities.

Research indicates that marijuana does impair certain areas of perception and cognition. In a study where people were given tasks to do while high it was found that, while performing these tasks was still within their abilities, more areas of the brain needed to be engaged in order to do so. Specific areas hindered by marijuana included slowed reaction times to sudden events, increased difficulty multitasking and decreased peripheral vision.

All of these affected areas could create problems while driving. However, there is research that shows that people who are high are aware of their impairment and take steps to accommodate that fact.

Studies looking into the chances of increased risk of accidents and fatalities resulting from marijuana impaired driving have yielded conflicting results.

States that have some form of legalized marijuana have also produced mixed results in their research aimed at determining the increased prevalence and risks of stoned drivers. Washington found a 25 percent hike in drivers testing positive for pot but could find no increase in accidents to coincide with the reported increase in drivers. States like California, Washington and Hawaii have reported increased accident rates but these studies have not successfully been replicated, insinuating an error in the research process.

One of the major barriers to determining the rate of people driving high and the rate of crashes caused by being high are the testing methods. Roadside saliva tests exist, and are often used, but they present a problem because the components being tested for can remain in saliva for several hours after the marijuana has been smoked. Blood tests also are able to detect the presence of marijuana long after its use. In those who smoke frequently, the test could come back positive for several weeks after use has stopped.

This issue with tests raises concerns from medical marijuana advocates that patients could be criminalized for medicating, even without having been high when behind the wheel.