Law enforcement officers from across Indiana have enrolled in a three-week training program to help them better detect drug-impaired motorists, reports RTV6.

Hosted by the Indianapolis Metropolitan Police Department, officers are learning to take vital signs and understand how drugs can impact a driver's pulse and blood pressure. They also learn how to do field sobriety tests, which include measuring pupils and having drivers touch walk and touch their finger to their nose, according to the report.

The Indiana police officers are training to become certified Drug Recognition Experts, a growing trend among law enforcement in several states.

In January, the National Highway Traffic Safety Administration provided funding to support Drug Recognition and Advanced Roadside Impaired Driving Enforcement training in five states including Delaware, Kentucky, Massachusetts, Oklahoma, and West Virginia as well as Guam.

Rapidly changing state laws regarding marijuana are having an impact on roadway safety. Presently, some form of marijuana use is legal in the majority of states. There are only nine states where marijuana use is completely illegal, according to DISA, a workplace drug testing service.

Although recreational marijuana is still illegal in Indiana, drugged driving is a growing problem on central state roads and in some communities has surpassed alcohol-impaired driving, reports RTV6.

Records show the most popular drugs of choice in Indiana are marijuana, opioids and stimulants; stimulants are on the rise, such as methamphetamine and cocaine.

But blood test results can take up to 10 months, which is another reason why DREs are needed to help get drugged drivers off the road.