THC happens to be the psychoactive component of marijuana, where both WSU chemistry professor Herbert Hill and a doctoral student are developing this idea so that it will end up being used by the local authorities in the same manner as that of a breathalyzer that detects whether someone is under the influence of alcohol or not.
Marijuana is legal for recreational use in Washington, Colorado, Alaska, and Oregon, but it is illegal to use it while driving, and in a 2012 study, a mere 30% of those under the influence of THC did not pass standard sobriety tests, while it takes up to 24 hours to obtain the results of blood tests. Hopefully a portable device like this could help accelerate detection a whole lot more.