The New York Times has an extensive front page article on the problem of drugged driving. While it’s long been illegal to drive while impaired – whether by alcohol or any other impairing substance – in North Carolina, law enforcement has focused on catching and prosecuting people who are impaired by alcohol.
That’s because it’s much easier to detect alcohol consumption – the smell, the fact that the person came from a bar, the fact that they refer to their drinking. In addition, where drivers aren’t truthful, but police have probable cause to suspect drinking and driving, police have a fairly inexpensive instrument – the Intox EC/IR – to test the person.
But testing people for medicines or other impairing substances requires either urine or, more properly, blood tests, which cost hundreds of dollar per person. That makes those tests much more cumbersome and expensive for law enforcement agencies to perform, and makes prosecution of driving while impaired with drugs ore medicines much tougher to do.