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Is there a chance of alcohol dissipating on a blood retest?

Mountain View, CA |

I've seen a lot of reasons for re testing blood, but it seems to me that there is a chance, especially with a high bac (say like over .20) that after a month and a half or whatever, some of the alcohol could dissipate between tests. is this accounted for in a retest? thanks!

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Attorney answers 4


If done properly the blood is put into a solution that helps maintain its proper level. There are many reasons to retest. What if the retest says .07? Then the first test was dead wrong. This lab people are cheaters. So many of them getting in trouble for various things including stealing the drugs, falsifying records etc.

I know of one case where the blood taken and tested was marked with another person's name. Well, if the blood was never retested, nobody would have known.

But almost always the blood its about the same. That is almost. What about the off chance it is not. That is why retesting the blood is important.

The above information does not establish an attorney client relationship nor is it meant to provide legal advice.

Hillary Johns

Hillary Johns


Great advice.


Just adding to Mr. Bogan's response, you never know. I've had cases where blood retests came back lower than what the DA's lab reported where the retest was done within 2 months of the original test. If an individual at the time of the stop agreed to take a PAS breat test at the scene of the stop and it came back at or about .20 and the blood test came back at about the same, unless a retest came back much lower or there was a problem with the way the blood draw was done, the preservative in the tube was insufficient, the blood was not refrigerated before the original test, or the blood type did not match the individual's blood type, it would be a tough case to fight. It doesn't cost too much to have blood retested so it is worth trying, especially if it number does not fit the amount of alcohol consumed during a certain period of time. There are different consequences in DUI cases where the blood alcohol is less than .20 and those that are .20 or higher. You should discuss all of this with an experienced DUI attorney in your area.


The blood sample should be properly maintained with the right amount of preservative, and refridgerated. Speak to a DUI attorney in your area. It's possible that a blood retest (often referred to as a blood split) could come back with lower or higher results. If the results vary enough either way it can be used as a defense.

Legal disclaimer: This message does not constitute legal advice and is for informational purposes only. This message does not establish an attorney-client relationship, which can only be established once a retainer agreement has been fully executed between you and this firm.


Yes, it is possible for the alcohol level in a blood sample to dissipate, but only likely if the sample is left open, topper off, so that the alcohol within evaporates. It is most likely that alcohol level will increase rather than decrease due to numerous reasons. Is dissipation factored in? No, two different tests on two different GC machines with most likely very dissimilar columns, controls and other factor differences.

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