But sometimes, errors occur that cannot be explained. As you can see in the above video, the Alco-Sensor IV DWF device simply would not accept my breath sample. I have blown into this and other breathalyzer and approved screening devices probably thousands of times. I have experimented with blowing hard, blowing soft, blowing for a short time, and blowing for a long time. I know how to provide a suitable sample. And in the video above, I was doing exactly what the device required to meet the sampling parameters. Yet for some reason, the device simply did not detect my airflow.
This was an approved screening device that had been checked for calibration using a wet bath standard and had received recent annual servicing. On paper, there was no reason why the device should not have accepted my breath sample. Nonetheless, despite my best and most legitimate attempts to blow, the machine did not work.
I deal with many Immediate Roadside Prohibition, Administrative Driving Prohibition, and criminal refusal to blow charges every year. Every once in a while I have a client who tells me they were making an earnest and honest attempt to provide a sample, but the police disclosure reveals information that would indicate no air was going into the device. Having experienced this issue myself, I can relate to my clients' bafflement at their circumstances and I understand my clients' innocence.
One of the most important factors in defending impaired driving, DUI, and/or Immediate Roadside Prohibition (IRP) cases is understanding the equipment used by the police. Until you have had hands-on experience with the devices and instruments, you cannot fully understand the intricacies of how these machines work. I am fortunate to have a small collection of breath testing equipment, including a BAC Datamaster C approved instrument, an Alco Meter SL-2 approved screening device, a Draeger AlcoTest 7410 approved screening device, and a Breathalyzer 900, which was formerly an approved instrument. In our office, we have an Alco-Sensor FST, Alco-Sensor IV, Intoxylizer 400, and an Intoxlyzer 5000. I have personally operated and used each of these pieces of equipment, so I know and understand how they work and why they fail.
But sometimes, (like in the above video) even with plenty of experience using a device, it simply does not work. And the reason why cannot be explained.