Accurately determining whether a motorist is impairment is critical when a police officer initiates a suspected drunk driving traffic stop. One option they have for doing this involves chemical testing. This is usually done through a breath test.
There are two primary types of alcohol screening machines: a preliminary alcohol screening (PAS) device and an evidentiary breath test device. Both are used to measure blood alcohol content (BAC), but they serve different purposes and operate under different legal and procedural guidelines.
Preliminary alcohol screening device
The PAS device is a portable breathalyzer used primarily in the field during traffic stops to quickly assess a driver’s level of impairment. This handheld device offers a fast and efficient way to measure a person’s BAC, helping officers make initial determinations about whether alcohol consumption might be a factor in suspected DUI incidents.
A PAS device is invaluable for its portability and convenience, providing immediate preliminary results that guide officers in their field assessments. PAS device use is typically voluntary. The results from a PAS device can give officers probable cause to arrest a driver under suspicion of DUI, but these results alone are generally not admissible as evidence in court for prosecution.
The larger evidentiary breath test device
The larger evidentiary breath test device is used after an arrest has been made, typically at a police station or a mobile unit designed for this purpose. This device is more sophisticated and accurate, so it provides results that meet legal standards for evidence in court.
The testing procedure is more controlled. It requires a specific breath volume and an observation period to ensure accurate and uncontaminated samples. They must also be calibrated on a regular schedule.
The results from these devices are considered scientifically reliable for determining a person’s BAC and can be used as direct evidence in DUI prosecutions. Due to their size, complexity, and the need for calibration and maintenance, these devices aren’t portable like the PAS devices but are crucial for the legal process.
Understanding the basics of these types of devices is crucial for defendants. Depending on the type of testing that they were subjected to during a stop and how their results were handled, challenging the testing process itself may favorably impact the results of their cases.
