Seattle DUI - what does quartz have to do with my breath test?

After a Seattle DUI arrest or an arrest for DUI anywhere in Washington state, the citizen who has been arrested for DUI will be asked to take a breath test. As of the date of this blog, the DataMaster breath testing machine (in two variations) is the only device approved for DUI evidential use. It operates by using infrared spectroscopy to analyze the breath of a DUI suspect. One of the issues that exists when an electro-mechanical device is used to produce forensic evidence in a DUI case is whether the machine is properly calibrated. The calibration process for the DUI breath test machine in our state involves running "simulator solutions" through the machine at various concentration levels and checking the electronics. However, there is always a question about how the machine is operating in the field. Therefore, as part of the calibration process, the DUI DataMaster takes a reading of a "quartz plate" that is designed to absorb a given amount of infrared light. Because the DataMaster ultimately produces an alcohol reading on a DUI suspect by comparing the intensity of infrared light in a breath chamber before and after an individual blows into it, the idea is that if the machine is consistently producing the same reading in the field on the quartz plate, it is accurate within a certain range of error. That's what quartz has to do with a breath test. The long and short of it is that despite many attempts to ensure the accuracy of infrared spectroscopy to produce evidential DUI breath test results, there remain a number of problems. As with other areas of Washington State DUI law, the technical side of defending a Seattle DUI is quite complex and requires in-depth knowledge of the technology used by DUI squad police in making DUI arrests and by prosecutors in prosecuting DUI cases.