Urinalysis to Determine Blood Alcohol in DUI Investigations

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The procedures used to analyze a DUI suspect's urine are basically the same as those used to analyze his blood: gas chromatography, enzymatic reaction, and the dichromate or Kazelka-Hines method. There are a number of potential problems with each of these procedures; the dichromate method is nonspecific for alcohol, for example, and gas chromatography is subject to radio frequency interference.

As with all methods of blood-alcohol analysis, DUI defense counsel should consider first the training and qualifications of the individual obtaining the sample urine. In many jurisdictions, this person, whether a police officer or a laboratory technician, must have received specific instruction in the manner of collecting, preserving, storing, and transporting a urine sample in drunk driving investigations. If the individual has not received the requisite training, the test results may be inadmissible in the DUI trial. At the very least, the lack of training should be brought out for the jury's benefit to cast doubt on the accuracy of the test results.

The laboratory, too, usually must be properly licensed and/ or possess a current certificate of inspection for the DUI test results to be admissible. And the technician who conducted the analysis must have received the required licensing from the appropriate agency. Counsel in a drunk driving case should always bear in mind the ever-present possibility of gaps in the chain of custody of the urine sample. The prosecution has the burden of establishing the possession and control of the sample from the time it was taken after the DUI arrest to the time it was analyzed.

As with blood analysis, it is necessary to add some type of preservative to the urine specimen to prevent decomposition. If the specimen has been permitted to sit for a few days before it is analyzed, it will begin to decompose due to bacterial action. And decomposition can have an interesting side effect: the production of alcohol in the specimen from the decaying process. Refrigeration will serve only to slow down this decomposition, not to stop it altogether. To prevent this natural decay, a preservative such as sodium fluoride or mercuric chloride must be added to the urine sample.

Failure to add a preservative -and it is not at all uncommon - should provide counsel representing a DUI client with sufficient material at least to discredit the test results and possibly to prevent their admission into evidence. Even if a preservative has been added to the sample, there is no guarantee that bacterial action will not have taken place. There are many different types of bacteria that can be found naturally in urine; if they are of the aerobic variety, they will produce reducing substances in the urine that can raise the alcohol level in the urine before the preservative can be added.

Where there has been a urine void, the DUI attorney should not overlook the discovery possibilities. Many law enforcement agencies require the DUI suspect to place a sample from the void into a vial. This sample is then collected and stored along with the second test sample. A primary purpose of this practice is to prove that there was, in fact, a prior void. If such a void sample exists, it should be included in any discovery request and, along with the test sample, analyzed by an independent laboratory. Any significant variation in the two analytical results can prove extremely valuable as defense evidence:

1. A significant disparity between the two samples in a DUI case indicates unreliability of the analyses.

2. A lower void reading indicates a rising BAC.

3. A higher void reading indicates a lower true BAC (since the test sample theoretically consists of about 20cc of urine freshly secreted into the bladder mixed with 20cc of stale urine remaining after a void, the test result reflects a contaminated average of the two: avoid sample of. 12 percent and a test sample of .10 percent, for example, means that the BAC of an uncontaminated test sample would have been about .08 percent).