Common Challenges to Blood Test Results in DWI Cases in NC
A blood test is conducted by drawing your blood and testing it, and it tends to be the most reliable testing procedure. However, this does not mean that the results are always right. If you are successful in challenging the result, the prosecutor may not be able to use the most important piece of evidence against you, and the charges against you may be dismissed. Questions regarding the reliability of the tests may also help to obtain a more favorable plea agreement where the charges are reduced to a much less serious offense.
There are a number of defenses to blood test results, and which one is applicable in your case will depend on your facts. Your experienced DWI attorney will be able to identify the best defenses in your case. Here are some defenses that may apply to your case:
- Lack of qualifications. The person administering the test must be qualified to do so. Your attorney can examine the training and experience of the person who administered your test to see if this is a basis for a defense. Even if the person was qualified, if there are other questions of his competency, such as cases of his falsifying records, this could lead to challenging the use of the blood test against you.
- Chain of custody. In DWI cases, the police are required to follow specific guidelines in handling the evidence—including the blood drawn from you and your test results. To ensure that they were not tampered with, the police must account for them at all times or the chain of custody may be broken. Mislabeling the test tube or misplacing it for a period of time are two examples of when the chain of custody might be broken. If the chain of custody is broken in your case, the blood test result could be excluded from evidence in your criminal case.
- Calibration. Blood testing machines often need to be calibrated, like breathalyzers, to ensure that they work properly. In some cases, the calibration of the equipment used in a blood test may not be properly done and could lead to an error in the results. In this situation, the test results could be excluded or the accuracy questioned.
- Storage. Blood samples must be properly stored or it can result in elevated error rates. The yeast, sugar, and bacteria in the blood can ferment if not stored correctly—which can lead to inaccurate test results. If your blood sample was improperly stored, the results may be inadmissible.
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