How PBTs Affect Probable Cause for DUI Arrests in California

 Posted on December 00, 0000 in DUI

In the state of California, police officers often use a Preliminary Alcohol Screening (PAS) test, also known as a portable or preliminary breath test (PBT), during a DUI stop to help determine whether a driver is under the influence. Although this roadside breath test appears somewhat informal, it can play a crucial role in establishing probable cause for an arrest.

While most people are aware that refusing a breathalyzer test can result in a driver’s license suspension, few understand the differences between the PBT and the breathalyzer tests used at the police station. The handheld PBT device is used at the roadside to estimate blood alcohol concentration and is generally used prior to a formal arrest.

In fact, in many cases, the results of the PBT actually provide the officer with the probable cause needed for DUI charges (California Vehicle Code 23152(a) and 23152(b)). So, should you refuse a PBT – and if you do, are there penalties for doing so? It is important that you fully understand your rights in this situation and that you speak to an experienced Sonoma, CA DUI lawyer as quickly as possible following your DUI arrest.

How Do PBTs Factor Into Probable Cause for a DUI Arrest?

Although a PBT breathalyzer only estimates BAC levels, it is usually administered after an officer has reasonable suspicion to believe a driver is under the influence. That reasonable suspicion could come in the form of erratic driving, the driver’s appearance, or speech. Based on the driver's driving behaviors or appearance, a police officer may ask the driver to participate in field sobriety tests and/or administer a portable breathalyzer test to test BAC levels.

Most drivers are not legally required to engage in either of these, and there are no penalties for refusal. The exception applies to individuals under the age of 21 or those on DUI probation. Drivers in either category cannot refuse a PBT test; doing so can result in immediate penalties. While refusal of field sobriety tests or PBTs cannot be used as evidence of guilt in court, the officer can testify about the refusal, which can influence the judge or jury.   

Although a PBT is used to establish probable cause, it is incorrect to assume that refusing a preliminary breath test means the officer has no probable cause for an arrest. The officer can still arrest a driver for DUI based on his or her observations, such as:

• Driving behaviors like weaving, driving exceptionally slow or significantly over the speed limit, or repeatedly crossing the yellow line.

• Slurred speech
• Bloodshot eyes
• A strong odor of alcohol
• The driver's admission of drinking
• Open containers of alcohol in the vehicle

There is a Significant Difference Between a PBT and the Formal Police Station Breathalyzer

While a PBT can be refused, the formal police station breathalyzer test cannot be refused without incurring a suspension of one's driver’s license. The portable breathalyzer test is much less accurate than the station breathalyzer and is more susceptible to poor calibration, improper handling, and even environmental conditions.

Environmental factors, such as temperature and humidity, can significantly impact the results of a PBT if the device is not properly calibrated to account for these variations. PBTs are also more susceptible to interference from other electronic devices than station breathalyzers.

This is not to say that station breathalyzers do not have their own share of potential problems. A knowledgeable DUI attorney may be able to challenge the station's BAC reading based on a driver’s specific illnesses, prescription medications, age, gender, profession, and more.  

Contact a San Francisco, CA DUI Lawyer

While a portable breath test result may seem minor, in some cases, it can be the tipping point that leads to a California DUI arrest. An experienced Napa, CA DUI attorney from Burglin Law Offices, P.C. can review your case, challenge probable cause, and fight for the best possible outcome.

Attorney Burglin has represented more than 5,000 individuals charged with DUI, has served as lead counsel in over 120 DUI jury trials, and is a graduate of the University of Indiana’s comprehensive course on chemical testing and scientific protocols in DUI cases. Call 415-729-7300 to schedule your free consultation.