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FIGHTING BLOOD EVIDENCE


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11/23/2011
James W Harwood
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Blood sample evidence is frequently used in California as evidence of intoxication in driving under the influence cases.  Out of the three available tests in California, blood is by far the most reliable and accurate.  This is because it is direct evidence of your BAC, whereas the other two tests are circumstantial evidence of the alcohol in your blood.  Despite the inherent accuracy of blood testing there are still ways for a skilled DUI attorney to challenge your results.

The first thing to look at is the manner that your blood was taken.  The requirements for proper blood collection are contained in Title 17 of the California Code of Regulations.  The blood must be drawn as soon as feasible to the alleged driving.  The blood must be drawn by a qualified individual.  A non-alcohol swab must be used to disinfect the needle site.  The needle and other equipment must be properly handled and sanitary.  Enough blood must be taken to allow duplicate testing by the defendant’s laboratory.  Finally, the blood must be immediately mixed with an anticoagulant and a preservative.  This is to make sure that the blood does not clot and that that there are no enzymes in the blood that will increase the BAC in the vial.

It is also critical that the entire chain of custody of the blood vial be scrutinized.  This is to make sure that the blood that was tested by the government lab was the same blood taken out of your arm.  It is also to determine if there were any periods where the blood could have been tampered with or improperly stored.  Any irregularity in the chain of custody could cast doubt on the integrity of the sample. 

Your attorney must also carefully study how your blood sample was tested.  After collection, samples are usually sent to a laboratory operated by the California Department of Justice or a particular county.  The close working relationship between these labs and the police and District Attorney should be pointed out to the jury as a source of bias.  Shortly after receiving the sample, the lab should test the blood in a machine called a gas chromatograph.  This machine basically heats a sample of the blood and measures the alcohol emitted.  This machine must be properly calibrated and maintained in order to provide reliable results.  Records from the machine must be turned over to your attorney for review.  The sample should be tested twice, but the lab must leave enough of the sample for later retesting. 

California case law used to allow any qualified witness from the lab to review the results of another analyst’s tests and testify to the results.  This meant that defense attorneys rarely had a meaningful opportunity to confront the blood test evidence.  However, the United States Supreme Court recently held that this does not satisfy the Constitution.  Now, the prosecution must call the actual scientist who tested the blood in order to use the results against you.  Often these witnesses are not available at trial, greatly increasing your chances of being acquitted.

While blood tests do not give a defense attorney as many flaws to attack, do not assume that there are no ways to challenge your test.  A skilled and experienced DUI attorney should be able to find any irregularities in your case, likely leading to a successfully outcome. 



Category: DUI and DWI Laws For California

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