Blood and Breath Defenses
Inherent Error Rate In DUI Blood and Breath Alcohol Testing
Even if the you assume that maintenance and calibration of the breath machine is perfect, the breath or blood test is administered exactly according to procedure, and no background or physiological factors exist that would produce false results. An inherent error still exists as to both blood alcohol testing procedures. Most experts agree the inherent error rate is about +/- .02 for DUI breath testing and +/- .01 for DUI blood testing.
Rising Blood Alcohol Level
To be guilty of DUI you have to have a blood alcohol concentration over 0.08 at the time of driving. If your blood alcohol concentration is rising when you are given the chemical test, you may have been under the legal limit at the time of driving. For example, you could blow a 0.11 at the police station but be 0.07 BAC when you got pulled over. Why? Because your blood alcohol level can increase by 0.02 or more an hour, if 2 hours pass from the time you are stopped till the time you are given a chemical test you could easily rise from 0.07 to 0.11. Alcohol takes as long as three hours or more to fully absorb into your bloodstream and create your peak blood alcohol level. This is critical if the DUI traffic stop occurred relatively soon after you finished drinking. You can see that even if your BAC was above .08 when the blood draw or breath test occurred at the police station (or hospital), it may well have been below .08 when you were actually driving. There is no law against having a BAC above .08 at a police station; it’s only the blood alcohol level while actually driving that counts for DUI purposes.
Failure To Comply With California’s Title 17 Regulations
California Code of Regulations Title 17 sets forth procedures that must be followed by anyone administering DUI blood or breath alcohol tests. Officers break these regulations all the time in DUI investigations. A failure to follow the regulations can expose the BAC test results to attack.
Radio Frequency Interference Can Produce Falsely High Results
Radio Frequency Interference (or RFI) can alter the results of almost any DUI blood or breath alcohol testing device. RFI can disturb the electronic circuitry of breath testing devices, gas chromatographs and mass spectrometers resulting in exaggeratedly high blood alcohol readings.Radio Frequency Interference emits from almost any electronic device, including police radios, police scanners, radar devices and computers. Studies have confirmed that RFI or electromagnetic interference can render a false BAC reading. That is why when you fly they tell you to turn off all of your electronic devices. If a cell phone can interfere with a plane’s electronics, then the police radios and scanners can affect the electronics on the chemical test device being used.
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