[SannTek]

Excellent point. The best solution to impaired driving would be a 100% accurate impairment test. The problem comes with designing and implementing such a test.

Let's start with what they have today, the standard field sobriety test. It is a pretty good test of impairment (with accuracy range between %75 to 90% depending on the study). However, there are several problems with the SFST. First of all, it requires police officers to be well trained and exercise their judgement roadside. This introduces the possibility for bias and the costs of training can sometimes be prohibitive. Secondly, the SFST cannot be administered in all conditions. A snowy day is a really bad time to be impaired, but also really difficult conditions for running a SFST.

The alternative is some kind of device that could detect the same (or different) markers of impairment as the SFST. The problem is making a device that is as accurate as the SFST, is portable, and easy to use is very difficult. If you look at attempts to date (like the Ocular DAX), these device tend to be really unwieldy and not even as accurate as the SFST. It seems like a technology that needs a little more time (maybe a decade?).

Overall though, definitely an avenue to explore.