Appellate Decision Explores Limitations of California DUI Breath Testing Device

Appellate Decision Explores Limitations of California DUI Breath Testing Device

Posted: 26 Jul 2011 02:51 PM PDT

California DUI breath testing is not always accurate. A recent California Court of Appeals case focused on the electrochromatograph/infrared (“EC/IR”) breath testing device and the possible limitations of that device when it comes to taking “quality” breath samples.

In People v. Vangelder, the defendant was convicted by a jury for driving with a blood-alcohol level of more than 0.08% in violation of California Vehicle Code 23152(b).

At the trial, the judge did not allow expert testimony challenging the assumption that the EC/IR device samples only alveolar (deep lung breath) air. That decision was prejudicial error, the Court of Appeal held.

“Although breath test results are admissible if a reliable foundation for them is laid,” the Court held, “we think that such competent evidence of their potential inaccuracy, because of physical variabilities leading to poor data in sampling, should have been allowed to be considered, as going to the weight to be accorded the testing results.”

The court also clarified that the issue was not “partition ratio variability,” ref erring to the application of the standardized partition ratio calculation for converting breath levels to blood-alcohol levels.

Inaccuracies in California DUI breath testing also can be caused by equipment malfunction, mouth alcohol contamination and rising blood alcohol level.

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