An increasing number of motorists in Texas and across the United States may be driving under the influence of marijuana. At the same time, however, the number of drivers operating their vehicles under the influence of alcohol has shown a strong downward trend.

Information on alcohol and drug use by drivers was presented in June 2017 at a meeting of the Research Society on Alcoholism. In the seven years between 2007 and 2014, there was a 50 percent increase in the number of drivers who tested positive for marijuana. Unlike drunk driving, driving after consuming marijuana does not lead to reckless or aggressive road behavior. However, marijuana can slow reaction times or a driver’s ability to respond to emergent situations.

Between 1973 and 2014, the number of drivers studied testing positive for alcohol declined by 77 percent. While the decline in drunk driving may be attributable to tougher laws as well as widespread alcohol education in the intervening decades, there’s no clear connection between marijuana legalization and the driving statistics. Many of the increases came prior to legalization or in states where marijuana is not legalized or decriminalized.

The information for the research was obtained by the National Highway Traffic Safety Administration. National roadside studies examine the prevalence of alcohol and other substances among drivers through gathering breath, oral fluid and blood samples from random drivers at 60 test sites across the country.

People who are facing charges of driving under the influence would be well-served by consulting a criminal defense lawyer. DUI charges can carry major penalties if a conviction is obtained. A defense strategy could in some cases include a challenge to the traffic stop as not being made with the required reasonable suspicion that a law was being broken.