Alcohol breath tests are often unreliable
I was recently called in for jury duty, as a Professor in the physical sciences - I'm rarely selected (although I love being on them.) The person next to me was an MD.Well the question was asked of both of us, (paraphrasing): "is a lab report the end of the conversion for you?" The MD basically was a 'yeah, why would a lab tech lie?' (very true - having been in industry myself).  However, I know how many ways something could yield poor results and must look at the whole picture.Whilst it is true that lab techs are not paid well enough to lie.  Lab techs are not paid well at all, and so this doesn't necessary attract the best of the best.  I've seen folks operating instruments that they had zero training on (as it was assumed that they saw it in school - not a good assumption of late.) Eg: One team I was an auditor for, didn't realize that the instrument they were using had effectively two (2x) ON/OFF switches - and the detector was turned off.  2 years of data had to be rejected.Now imagine a completely untrained cop with a black box, that's been bouncing around in their trunk - what could go wrong?... /sI guess what I'm saying:  field tests are highly suspect, and even lab tests need to be carefully considered - all of which requires a solid grasp on scientific/critical reasoning (which is in short supply.)