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How long can a BAC blood sample survive?

Cherry Hill, NJ |

Thirteen months ago, a blood sample was taken from a friend immediately following an accident. Upon arrival to the hospital, another sample was taken: that sample read .057. The first test's results didn't exist until last month, and came back as a .08. I'm mostly wondering why it took so long, and if it's even possible that original sample still existed in good enough condition to be tested positively after so long. And if so, then why did the two samples have a .027 difference; what's the rate that alcohol clears an average human being's system?

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Attorney answers 4


You are asking the right questions, and they are good questions. Another question is why is the case so old? These cases usually resolve much more quickly. If your friend has a lawyer, this needs to be discussed with the lawyer. If not, he should get one to challenge the questionable results and procedures.


The sample will degrade over time and become unreliable if not stored properly. Blood alcohol level rises and falls on a bell curve. The question is not whether the person was intoxicated at the time the sample was taken but whether they were intoxicated at the time they were driving. A first sample less than the limit and a second sample over the limit would tend to indicate a lower level at the time of the offense because the blood alcohol level would not go up, down and then up again.

My answers are only intended as general legal advice based on my eighteen years as an Austin criminal defense and DUI attorney. They are not intended to be a binding legal opinion nor to create an attorney - client relationship. For those questions asked outside of Texas, there is no intent on my part to practice law in any other state There is no substitute for contacting a local attorney. Feel free to visit my website, .


Your friend has an excellent defense case. I agree with my colleagues, the State has many questions to answer before the higher results would be allowed in Court. No matter the ruling the hospital results can also be entered and the State would have to proof why the difference. Remember they must prove guilt beyond a reasonable doubt. The chain of custody and the manner of preservation is theirs to prove and if the first sample did or did not deteriorate. On the other hand the second test may not have been done for some hours and "blow off' may have occurred (figure .015/hour). They are many questions to be answered. Have him call for a free consultation.


I agree that there are significant issues to exploit in defending your friend's case. I would be curious to know under what circumstances a sample was taken at the scene. If proper procedure for a blood draw isn't followed, the sample could be deemed unreliable and the evidence could be suppressed. There are also search issues that can be raised depending upon the circumstances. Your friend should speak with an experienced DUI attorney right away. My office is at your disposal should you require assistance.

This response is for informational purposes only and not intended to be legal advice or in any way create a lawyer-client relationship. You should always speak directly with an attorney with any legal questions you may have.

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