Before a police officer can lawfully arrest you for DWI, they must have probable cause to believe that you were intoxicated by alcohol and/or drugs. Probable cause means that there is some concrete evidence they can point to justifying their taking you into custody.
One way an officer can establish probable cause is by subjecting you to a series of field sobriety tests. A preliminary alcohol screening (PAS) may be a part of this initial assessment.
Essentially, a PAS is a roadside breath test administered to determine the level of alcohol in your system at the time of the stop. If the results indicate that your blood alcohol concentration is elevated, the officer may lawfully arrest you.
How Does the PAS Measure Alcohol Concentration?
When you drink alcohol, it gets absorbed into your system and processed by the liver. The liver can only process about one standard drink per hour. The remaining alcohol will move through your system, and with some passing through your lungs.
The PAS breath testing machine determines alcohol concentration by analyzing the amount of alcohol in your system when you exhale.
Is a PAS Accurate?
A breath test is not necessarily as accurate as a blood test, especially when done with the type of handheld device police officers use on the side of the road. These machines, and other breath analyzers, do not directly measure blood alcohol concentration. Instead, they show an estimate of the percentage of alcohol in your system.
That said, regardless of the accuracy of a roadside breath test, an officer may still use the results to justify a DWI arrest.
Can I Refuse a PAS?
As with other field sobriety tests, the preliminary alcohol screening is not required – though an officer may make it seem like it is because of the way they phrase their request. You can refuse to provide a breath sample for the roadside test.
If you decide not to participate in the pre-arrest breath test process, you can politely inform the officer of your refusal. You will not face any criminal or administrative sanctions for not taking the PAS.
However, refusing the preliminary breath test does not mean you will not be arrested. The officer can rely on other evidence to establish probable cause.
Does the PAS Satisfy Requirements Under Texas's Implied Consent Law?
Texas's implied consent law under Transportation Code § 724.011 provides that any person lawfully arrested for driving while intoxicated is deemed to have given their consent to be subject to a chemical test to determine alcohol concentration. The law applies to post-arrest blood, breath, or urine tests, not pre-arrest analyses.
Thus, even if you provided a breath sample during the initial DWI stop, you are still legally required to participate in a chemical test after your arrest. In other words, the PAS does not satisfy requirements under implied consent.
Refusing the post-arrest chemical test will subject you to various consequences. First, you will lose your driving privileges for at least 180 days. Second, your refusal will be admissible in court.
What Do I Do If I Took the Preliminary Breath Test?
If you submitted to the preliminary breath test – or even the post-arrest chemical test – all hope is not lost in your case. Various factors could have affected the results, and questions may be raised about the legality of the initial DWI stop and your subsequent arrest. Consult with a criminal defense attorney about your case to learn more about your legal options.