Incorrect Blood Test Results Lead to 'Reluctant' DWI Dismissal

Lawrence Taylor writes about an interesting dismissal in one of his California DUI cases, although it could have happened in a Texas DWI case just as well.
His client’s blood test results came back from the lab well over the .08 limit, in fact a .15 blood alcohol concentration.
According to the defendant, his body weight, his drinking pattern, his likely stomach contents etc., the blood test had to be wrong. Or, the result had to be wrong for him to be innocent.
So they had the blood sample tested for the presence and amount of preservative and anticoagulant, the absence or low levels of which could cause false high results. Alas, no problems there – the result still looked admissible, and no clear line of attack for the defense.
With the two most likely explanations of false high blood test results out the window, the next most likely explanation (of innocence anyway) became that the blood being tested was not the blood drawn from the client.
[See also Mark Bennett’s blog for a related discussion of the intersection of scientific principle with criminal defense lawyering in Occam’s Razor and Bennett’s Chainsaw. For those that know the second principle, the phrase ‘DWI dismissal’ in the title of the post will be a hint that Mark’s ‘most likely explanation of the evidence’ theory is not in play here.]
Checking the blood type of the sample against the blood type of the DWI defendant is the easiest, or perhaps cheapest method of proving that the State has the wrong blood, although it is not foolproof. In Taylor’s case they checked and… it was the same blood type. It’s not discussed in the post, but as long as we are talking about math and science, it’s worth noting that principles of conditional probability and specifically Bayes’ Theorem tells us this now makes it more likely that it was indeed the client’s blood. But it’s not conclusive by any means. It was Type O, which puts it at the most common blood type, about 40% of the population.
Now, I’ve seen Lawrence speak at various seminars over the years, and I think he is to say the least an impressive DWI lawyer. So the next step in the process doesn’t surprise me:
We decided to try something different, something that, to our knowledge, had not been done before in any DUI case. We had blood taken from our client and, with a portion of the remaining sample from the LAPD lab, shipped to a laboratory in Oklahoma that specialized in DNA testing.
A month or so later the report came in: the blood tested by LAPD was conclusively not that of our client.
It’s a great post. DWI lawyers in Texas and everywhere else should read it. He goes on to talk about chain of custody, gas chromatograph instruments, and how it’s likely that other DUI defendants in the same ‘batch’ as his client also probably had their blood samples misidentified with them. Some of them ended up with lower results than they really had, some higher. (And unfortunately, we all know that most of them couldn’t afford this type of sleuthing for justice.)
So what’s the ending here? Well, this line, really a throwaway line in light of the substance of the post jumped out at me:
The prosecutor in the case initially refused to accept these results. But after we proved that the comparison blood had come from our client and after LAPD checked the blood themselves, he reluctantly dismissed all criminal charges. [Emphasis Added]
Yes. When the State is pressured to convict all who come before it on DWI charges, prosecutors can become downright reluctant to dismiss the case, even in light of these facts. Thankfully in this case, they took their duty as prosecutors seriously.
One last note: I thought about titling this post ‘Incorrect Blood’ Test Results… but then, that would have given away the punchline.