https://en.wikipedia.org/wiki/Blood_alcohol_content#Highest_...
I think anyone who has played with a personal breath test device knows that you can get false readings quite easily, but blood tests are something else altogether.
Bizarre
the wrappings were subsequently soaked with 200 ml of 95% (v/v) ethanol. Although the ethanol-soaked cotton was kept covering the skin with rubber sheeting and adhesive tapes for 4–9 hours, no ethanol was measurable in the blood.
Nobody wants to talk about the (in)accuracy of breathalyzers.
That's because like every other bit of tech used to convict people it's designed to err on the side of convicting people not being accurate.
If you want a laugh look up the sensors they use in the alcohol ankle bracelets. Then look up the OEM specs, calibration requirements, usage environment requirements and accuracy claims by the vendors and try and reconcile the two (several research papers have been written about this). The whole industry is lousy.
I'm skeptical that a case would be thrown out that easily. I have seen expert witnesses getting chewed by the prosecution on minor details. So what if the source is unavailable. It can be argued that the device is tested and regularly calibrated, and that any inaccuracies found will be minor - and certainly not enough to exonerate the defendant.
Yeah maybe there might be some inaccuracy - but then the defendant failed the standardized field sobriety tests. And the cop is saying that they were visibly drunk. Now what?
You pay to have a medical expert come in and explain the myriad conditions that can lead to failing the field sobriety tests. It's simply a question of funding. Even if the case isn't dropped the jury will almost certainly have reasonable doubt.
This is partially why, at least in California, major parts of the penalties for DUI are "administrative" in nature and handled by the DMV.
Even if you do get acquitted in criminal court, it's another set of hearings to get your license back ($$$), lose the special "I got a DUI" SR-22 insurance requirement, etc.