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Mark L. Deniz, Esq.

Hand held breath test is not a chemical test. intoxilyzer. breathalyzer. Do not let a field sobriety test gizmo substitute for a chemical test. A breakdown by a San Diego DUI Defense Attorney Lawyer. Fighting breath tests.

by | Aug 2, 2019 | Firm News |

The preliminary alcohol screening device, also known as the PAS, is a handheld device used to detect alcohol in the blood in a San Diego DUI case. This is one of the standard field sobriety tests (FSTs) that are used when someone is detained due to suspicion of driving under the influence of alcohol (DUI). Officers use this test, among others, to determine whether to arrest someone for driving under the influence. The PAS test is usually the final field sobriety test (roadside test) before the officer makes the decision whether or not to arrest.

The PAS device used by officers is the Alco Sensor IV or the Lifeloc (CHP). This device uses the Black or green Dot versions which sometimes allows tests to be stored and printouts of the results to be available. If alcohol is detected, the officer must wait two minutes before the device is ready to be used again. The reality is if the officer has a device that has a printout device they will not use it.

The confusion that people have is this device is not a chemical test but just another field sobriety test. The PAS device does not have the safeguards that are needed to have the device

be deemed a “chemical test” under the implied consent law. Where California law has people needing to take the chemical test upon an arrest there is no such laws for the PAS (unless you are under 21 or on probation).

Even though the PAS is not a real chemical test but merely a field sobriety test the prosecution will use the PAS results (which is usually high because there are not adequate safeguards) in the theory of the defense. An examination of the facts by an experienced San Diego DUI attorney can sometimes actually use the PAS results to your benefit. It is key to be proactive and call our office now for a free consultation at 858-751-4384.

How Does the PAS Device Work?

The PAS device works by detecting alcohol in the deep lung air, also known as the alveolar air, from the lungs. This means that when someone breathes into the PAS device, it is important that they blow enough air to ensure that alveolar air is obtained. An issue with this arrises when the deep lung air is not taken, and the tests reflect a higher blood alcohol level due to not collecting the avower air. This is where a good DUI attorney can help to spot these potential issues.

The alveolar air collected is more equal to the blood alcohol than breath than breath collected when a person first exhales. Most PAS devices have what is called an automatic trap, where the device automatically determines how much air to retrieve from a person. The automatic trap will take one cubic centimeter of air from a person’s breath through the machine. However, some issues may arise when officers decide to use a manual trap rather than the automatic trap.

What is a Manual Trap?

When an officer uses the manual trap it means the officer manually decides how much air to take. The officer usually decides to use a Manual Trap when the person taking the test is having a hard time blowing into the device. While the automatic trap will take one cubic centimeter of air from a person, when an officer uses a manual trap that may not always be the case. An officer may take less air from a person when using the manual trap. This is important because it may cause a higher reading due to the possible lack of the alveolar air. Because the alveolar air is what will more accurately reflect the blood alcohol concentration, when an officer uses a manual trap they risk not getting enough air and thus not obtaining the alveolar air. A manual trap has more of a chance in getting mouth alcohol and other substances that it may believe is alcohol.


So much of a DUI defense case examination has to do with reviewing the police officers conduct and the machines they use. People and machines make mistakes. One common mistake is the police do not properly admonish someone that they have a right to refuse the PAS device. It is a field sobriety test. What some police do is casually bring people along in the field sobriety tests one by one never telling them that these tests were all voluntary. If they do not properly advise someone of their rights on the PAS device the test results may be thrown out.


It is important to obtain a San Diego DUI lawyer that understands all of these issues. People look at these blood alcohol numbers and say, “well I guess it is so” when it is not. This device especially is merely a field sobriety test. Mark Deniz was a senior prosecutor for almost 10 years. He runs a practice with a primary focus on DUIs. If you or a loved one has been arrested for driving under the influence, it is important to be proactive on your case an hire an experienced DUI attorney who knows these issues and will look to see if you have them in your case. Call 858-751-4384.

Hire a Proactive, affordable, and quality defense when you are facing San Diego DUI charges. Whether you have been charged of a San Diego DUI, Poway DUI, La Mesa DUI, Santee DUI, Mission Valley DUI, Clairemont DUI, Point Loma DUI, La Jolla DUI, Carmel Valley DUI, Mira Mesa DUI, Pacific Beach DUI, Del Mar DUI, Carmel Valley DUI, Encinitas DUI, Oceanside DUI, Escondido DUI, Vista DUI, San Marcos DUI, Carlsbad DUI, El Cajon DUI it is vital you need to hire an attorney who knows how to defend your rights and can determine if the government can prove their case. Contact the Law Office of Mark Deniz now for a free case evaluation at 858-751-4384.