As New Jersey moves to legalize weed, the state may face a new challenge: how to handle driving while stoned.

Critics of a bill to make cannabis legal warn it could lead to more drugged-driving cases and unsafe highways. But lawmakers say heightened police training and drug enforcement will keep the problem in check. Others say arresting people for driving while high and prosecuting could wreak havoc in the courts.

Consider the case of a South Jersey man who was charged with two counts of vehicular homicide after his pickup truck struck and killed a jogger, hit a tree, flipped over, and then killed his passenger. A blood test revealed that he had a small amount of THC — the psychoactive compound in cannabis — in his blood after the 2015 accident. Last year, a jury acquitted him.

That case and several others highlight an often-overlooked problem that could be exacerbated if marijuana is legalized in New Jersey. What about people who test positive for cannabis — due to previous use — even though they are not actually intoxicated at the time of an arrest or accident?