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What Is The Procedure For Evidential Breathalyzer Test In A DUI Stop?

Two different breath tests are potentially taken. One is at the initial stop for a possible DUI stop, and one is the preliminary alcohol-screening test. This test is optional folks are not required to take a test. The other breath test is known as the evidential test. Once a police officer has a probable cause to pull someone over, initiate a DUI investigation, and potentially arrest someone for a DUI, the last field sobriety test will be the breath test, and call it a preliminary alcohol-screening test. They will be asked to blow into a device two times. This will determine whether they are at 0.08%, or greater alcohol level.

If someone blows higher, almost certainly they will be arrested for a DUI. If they do not, they may still be arrested if an officer believes they are under the influence of drugs, alcohol, or the combined influence. Therefore, it is usually not advisable to blow into these machines, the preliminary ones, remember, are not optional. However, if an officer believes that they have enough evidence to arrest you for a DUI, even without the odor of alcohol on your breath, they may observe other symptoms, such as the fact they do not feel you showed a level of sobriety. Once you have been arrested for a DUI, the police officer is required to read an admonishment, which says that you have consented to taking a chemical test, the breath, or a blood test at the time of your arrest.

At this point, you have been arrested for a DUI, you are admonished as to your choice of testing, and you are required to do either a breath, or a blood test. Typically, if you choose a breath test, they do not have a different device to do this testing. They will take you to a police station, a holding area, or jail, and then take the breath test. They will have you blow into the machines twice. You blow twice because they are required to have two blows within 0.02seconds of one another. Sometimes, they might ask someone to do multiple blows, because they are not getting enough of a breath sample, or someone is not blowing hard enough, or maybe there is something wrong with the machine, which is what we hope in a defense case.

The evidential test is used against you in court. Sometimes the preliminary breath test, in fact many times the preliminary breath test is something that the prosecutor will try to use it against you, especially if the number is higher than the evidential test. This shows the time you were driving, and you may have been even higher than you were later, when you did the evidential breath test. Another type of testing that you have the option to do if you do not choose the evidential breath test is a blood test. That is supposed to be done in a medically approved setting, usually by a phlebotomist, a nurse, or someone who is trained to take blood. That is usually done at the jail, or at a police station, rarely has it ever been performed in the field.

Sometimes, it is performed at a hospital. It just depends on where they decide to take you. They draw one to three vials of blood, which are supposed to be properly stored, and tested to determine your blood alcohol level.

How Does The Breathalyzer Machine Determine The Level Of Alcohol In A Person’s System?

The breathalyzer machine takes a deep long sample called an alveolar sample, which comes from your lungs, and depending on what kind of machine it is, it can be done using fuel cell technology, or it can be one that uses infrared technology, or it could be both. The results have a formula, and it converts breath numbers to blood, so your breath result is a specific number. Then they have a mathematical equation in the software of the machine, which converts it to a number, which in turn gives a blood alcohol reading.

There is less of a margin of error if it is a direct blood test. However, there are more things that can go wrong with blood testing. People often ask should I do a breath, or a blood test. In most counties, the blood test would be something that would have more defenses for things that could potentially go wrong with the testing, or the machine. With breath testing, unless you are in the San Francisco County, in the bay area, you are better off doing a blood test in most cases. However, if you have drugs in your system, like marijuana, or other drugs, and the officer is not suspecting that, doing a blood test may get you in more trouble, so you need to consider that.

As I was saying earlier, in San Francisco, they have very old breath machines. It is called an Intoxilyzer 5000. That is one place where doing a breath test still gives us plenty of opportunities to attack a very old archaic machine. It has too many fail-safes than the other ones do.

For more information on Procedure For Evidential Breath Test, a free initial consultation is your next best step. Get the information and legal answers you are seeking by calling (415) 523-7878 today.

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Aaron Bortel
With 30 years of specialized experience in DUI defense, Attorney Aaron Bortel is a dedicated advocate for those facing DUI charges in the Bay Area. Committed to helping clients avoid jail, save their driver’s licenses and jobs, and prevent permanent criminal records, he combines deep legal expertise with genuine care for his client's welfare. Trust in a lawyer who not only defends but truly supports you through challenging times.

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