Some people drive high.
They shouldn't, but they're high, so they don't really know what's good for them and what isn't.
Should they get stopped by police, the long nose of the law can sometimes sniff the presence of marijuana in their car.
Should they happen to have nosed their way into some cocaine, there might be traces of white powder around their nostrils.
As yet, though, there hasn't been a machine that can detect the presence of such drugs on one's breath, as there is for alcohol.
Scientists in Sweden, however, believe they have made some progress in creating such a device.
As the Smithsonian magazine reports, sober minds at the Karolinska Institute in Stockholm decided to use an already available breath sampler (created by them) called SensAbues, which claims to analyze breath samples using chromatography and mass spectrometry.
This, allegedly, offers "legally defensible" results.
So the scientists put together a mouthpiece and a microparticle filter and asked 46 patients from a drug clinic to breathe out.
It seems that the small particles that give away drug use get into your prettily named airway-lining fluid. It is these particles that the breath machine tries to trap.
The researchers claim they found traces of many drugs, including pot, cocaine, meth, but also morphine and diazepam.
Here's the part that some might find disturbing: these results were achieved 24 hours after the subjects had actually taken drugs.
This might surely suggest a certain complication in any potential police use of such a device.
Are you fit to drive 24 hours after smoking pot? Will there be a certain threshold of drug presence that will signify a safety line? And does the presence of drugs on your breath signify that there are any significant amounts in your actual system?
There's another little kink here. In 23 percent of the samples taken, the machine declared that it had detected drugs when none had actually been taken. Yes, the dreaded false positive still lurks.
Currently, the machine's results have to be sent to a lab for analysis.
But one can surely imagine in a not-too-distant future that your friendly local policeman might have another tool at his disposal to examine just what state you are really in. "Texas" may not be a sufficient answer.