Challenging Evidence from Breath Tests and Blood Tests — DWI Defense Louisiana

New Orleans DWI DUI Attorney 

Elizabeth B. Carpenter, Esq. —  DWI DUI Attorney New Orleans 



Serving DWI DUI Clients In Metairie, Kenner, Gretna, New Orleans, LaPlace, Hammond, Mandeville and Covington!



By Elizabeth B Carpenter

Challenging Evidence from Breath Tests and Blood Tests


One of the first forms of testing that is often utilized in Louisiana DWI investigations is that of the breath test, commonly taken with what is known as the Breathalyzer. This test is simple and requires that the subject breathe into a machine which samples the breath. This can then deliver a reading on the blood alcohol concentration (BAC) of the subject; if it is over 0.08 percent it can give the law enforcement officer evidence to arrest for drunk driving. This, however, is often a test that can be prone to error and can result in serious erroneous readings.


For example, should the defendant fail to take a deep breath, it can cause them to breath from their mouth instead of deep from their lungs – this can cause a faulty reading. Similarly, if there is the existence of mouth alcohol or if the test is administered in the absorptive phase, then the reading can’t be trusted. The most common source of error, however, is the fact that these machines are incredibly delicate and require consistent calibration to ensure that they are working. If they are not maintained perfectly on schedule, an experienced attorney will be able to work with you to combat the evidence.


The blood test is commonly believed to be the most reliable form of testing and in many ways this is true. This form is test requires that a blood sample be drawn and then sent to a lab for testing. While this is scientific and very formulaic, it can still be prone to error. One prime example of a cause of error is the fact that the sample is required to be stored in a very specific manner. If it isn’t (for example, if preservatives aren’t properly mixed in or anticoagulants not used), then the sample can “go bad.” Another source of error is that the chain of custody can somehow become broken – making it an unreliable form of evidence.




When you are dealing with criminal charges pertaining to drunk driving, you need an aggressive attorney that you can rely upon.  Contact DWI DUI Attorney Elizabeth B. Carpenter — Available 24/7 to help you.

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By |2012-09-16T19:15:18+00:00September 16th, 2012|Categories: DWI DUI|Tags: , |
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