With voters in Colorado and Washington State giving the green light for recreational marijuana, police face a new challenge. They’re making sure folks know that while state law says it’s okay to light up, Uncle Sam still frowns on federal grounds. Even more importantly, hitting the road while stoned? That’s a big no-no. This means drivers need to keep their wits about them. So, why not dive into how this change shakes things up?

Driving under the influence of drugs or alcohol is illegal in all 50 states and police frown on this activity, showing little mercy for drivers caught driving while impaired. In some cases the substance which the driver is under the influence of is legal (like alcohol) or illegal (like prescription drugs or marijuana.) Just because marijuana is now legal in Colorado doesn’t suddenly mean it is legal for drivers to operate a vehicle under its influence.

In fact, because the recreational use of marijuana is now legal police are anticipating an increase in the number of drivers who might be under its influence when they climb behind the wheel. Marijuana is known to slow reaction times and judgement in users, which is a true detriment to someone trying to navigate roads and bridges in a 3-thousand pound missile made of steel, glass and plastic.

Police are now equipped with test kits to determine if marijuana is present on a drivers person, and a simple blood test, which drivers must agree to upon request by police or forfeit their license, is as quick as a trip to the local hospital.

In 2007 the National Highway Traffic Safety Administration discovered that 16 percent of drivers stopped during weekend driving were positive for drugs (besides alcohol) and when they checked again in 2009 that percentage had increased to more than 30 percent. This means that although the use of marijuana is illegal practically everywhere many drivers are still under the influence. Now that it is legal in some places, police are bracing for what they perceive will be a big increase in the number of drivers they catch who are ‘driving high.’