Aside from agility tests, police have had no technological way of detecting the use of controlled substances by drivers other than for alcohol. Cheech and Chong could merrily drive down the highway in their van made out cannabis and be stoned out of their minds and there was little that the police could do to prove it.
According to this rather colorful article, which uses terms like “stoners and dopers,” Philips has developed a hand-held device that employs nanotechnology based on the use of electromagnets and nanoparticles to “separate the sober from the impaired”.
The article points out that the Netherlands-based Philips will roll this out initially in Europe. But oddly the article raises the specter of the device being a “privacy-invading drug tester.” I am not sure how much privacy you are entitled to when driving impaired on a public road, but in any case I sure this is not the kind of invasion of privacy caused by nanotech that has some so concerned.