When a person is arrested on suspicion of drunk driving, the arresting officer will perform field sobriety tests to confirm if the person is impaired. When the arresting officer suspects the person to be intoxicated by alcohol, he or she may request the suspect to submit to a breathalyzer test. A breath test is supposed to measure the alcohol content in a person by breathing into the device. The results of the test give an indication of the available alcohol in the suspect's system in comparison to the legally acceptable level. Unfortunately, breath tests are not 100% accurate, yet you can be charged with a DUI offense from the results. When this happens, you need a DUI lawyer to fight the allegations. At Orange County DUI Defense Lawyer, we are committed to helping our clients overcome these allegations.

Administering a Breathalyzer Test

There are two kinds of breathalyzer tests for DUI offenses. These tests are administered in two stages if necessary:

  • When pulled over for suspected drunk driving or at a DUI checkpoint, the officer will perform a preliminary alcohol screening test (PAS) and
  • After being arrested for alleged drunk driving, a suspect may be asked to agree to take a breath test at the police department offices.

Here, we discuss these two breath tests in detail for ease of understanding.

Preliminary Alcohol Screening Test (PAS)

This test is administered when an investigation for a DUI is going on. This is typically applied by the roadside when a person is pulled over for suspected drunk driving or at a sobriety checkpoint. Usually, before a person is arrested for drunk driving, the test is carried out to determine if to arrest the suspect or not.

The test is administered using a handheld device similar to a breathalyzer. Many drivers can decline to take the test and are free to decide if they want to take the test. However, some drivers do not have the privilege of declining. These are:

  • Drivers currently serving a DUI probation
  • Drivers below 21 years and are suspected of underage drinking and violation of the law on zero tolerance to underage drunk driving

Consequences of Refusing to Submit to a PAS?

If a driver is below the age of 21 or is serving DUI probation, a decline from taking the test is assumed to be a refusal to submit to a breath test in California. This act will lead to an automatic suspension of your driver’s license irrespective of a DUI conviction.

A PAS is one of the field sobriety tests an officer may perform on a suspect. It helps determine whether the suspect can be arrested for drunk driving. One can refuse to take the test if he or she does not fall under any of the above two categories. However, there are consequences to this.

  • If prosecuted for a DUI offense, the DMV will automatically suspend your license for a year
  • If you are convicted of a DUI offense, you will serve a mandatory jail sentence of 48 hours besides the other penalties

When you are suspected of drunk driving, you can opt for a blood test instead of a breath test, and there are no consequences for that. If you are convicted of the offense of declining to submit to a chemical test, the court can still allow you to drive if you install your vehicle with an IID device.

Evidentiary Portable Breath Test Device

In Orange County, among others, law enforcement officers can conduct breath tests on a portable device after arresting DUI drivers. This device is known as a Portable Evidential Breath-alcohol Testing system (PEBT). It is a handheld device used for preliminary screening by police departments. The device can be connected to the printer, and the results of your breath test recorded.

DUI lawyers will advise their clients not to submit to this test when they are arrested. Instead, it is best to request a blood chemical test.

Evidentiary Breath Test Post-Arrest

Every driver arrested for suspected drunk driving must submit to a DUI chemical test. An after arrest test referred to as the evidentiary test is taken. This is even though they may have submitted to a PAS test.

Most drivers have the privilege to choose between a blood or breath test except when:

  • The arresting officer has a reason to believe the suspect was operating the car while intoxicated by drugs. Because of this, they will request the driver to take a blood chemical test
  • The arrested suspect is unable to breathe into the device sufficiently to allow a breath test to be carried out
  • The suspect is dead or unconscious
  • If the driver was involved in an accident, he or she might have been rushed to the hospital where a breathalyzer gadget is unavailable

Which is a Better test, Breath, or Blood Test?

In the legal fraternity, no consensus as to the better test of the two exists. Each has its advantages and disadvantages. A breathalyzer test, however, takes a short time and is non-invasive. However, the tests are accompanied by many errors, as we shall discuss in detail. These errors challenge the accuracy of the results and are a basis for defense strategies in a DUI case.

On the other hand, blood tests have the advantage of having a part of the drawn blood saved should the defendant want to seek independent testing. Unfortunately, breath samples cannot be preserved, making it challenging to dispute the results of a breath test or take independent tests.

All in all, the type of test, though essential, is not the primary factor in consideration. The most significant factor is if the police complied with the procedures of Title 17.

Title 17 Guidelines on Breath Tests

California has set forth regulations for taking a breath test under Title 17. The police officers and laboratories are expected to follow the procedures when taking breath tests. When the rules set forth or the process is compromised, the results of the BAC will be equally compromised. A DUI lawyer knows when to use these mistakes in fighting a DUI charge for their client.

When the mistakes are made, a lawyer will file a motion, excluding the results of the breath test, according to PEN 1538.5. Should the judge agree to the petition, the readings will be inadmissible in court as evidence. When the prosecution is unable to present the BAC results of the defendant, it becomes challenging to prove the suspect was drunk driving. As a result, your lawyer and the prosecution may have to discuss a plea bargain that will lead to reduced charges or a dismissal altogether.

There are various rules under Title 17 that regulate breath tests. These are:

  • The device for breath testing should always be stored in optimum working condition
  • The maintenance of the equipment is essential. After 150 uses or ten days, the device should be calibrated
  • The person administering the breath test should be well trained in using the device
  • The suspected drunk driver should be kept under observation for fifteen minutes prior to giving a breath test. In the monitoring process, he or she should not smoke, take anything in their mouth like food or a drink, must not regurgitate, vomit, or burp. All these can increase the level of alcohol in the mouth and result in false BAC results
  • The person administering the test must ensure the breath collected is deep from the lungs
  • The administering officer is required to take two breath tests, and they should not be too varied with over 0.02 grams for every 100 milliliters of blood alcohol
  • The laboratory charged with taking the test must have a detailed record of how the device is periodically calibrated. This is in addition to the results from the test

Violations of Title 17 and Elevated Breath Test Results

When the regulations as stipulated in Title 17 are violated, the results from the breath test can be wrong or false. Increased BAC results can be due to three issues. These are:

  • The device for taking the test was not calibrated properly
  • The operator of the device made mistakes
  • The records were not kept as expected under the law of California

During a DUI defense, a lawyer will get all these records and analyze them for errors. The lawyer will also check to see if the person that carried out the tests:

  • Ensured the defendant’s mouth was empty
  • Was able to continuously monitor the defendant for fifteen minutes prior to the commencement of the test. Whether the administering officer checked to ensure the defendant did not regurgitate or burp
  • Had the mouthpiece adequately attached with the machine
  • He or she recorded when the fifteen-minute observation period began and
  • Made a record of the time when the defendant blew into the device.

Understanding How Breath Testing for Alcohol Works

A DUI breath test checks the quantity of alcohol a person has in their breath or air. The breath is from deep in the lungs, known as alveolar. The alveoli are shaped like balloons surrounded by many capillaries. These capillaries allow oxygen to pass to the blood from the lungs. They are the transit where other wastes such as alcohol or carbon dioxide pass through from the blood. This is how deep breathing or blowing can capture the alcohol in your blood.

To understand the working of breath tests, you need to take into consideration how the air comes out of the lungs while exhaling:

  • It exits through the nose or mouth
  • Moving up the throat and the airway and
  • Coming from deep in the lungs

Alveolar air is the deepest and last to exit from the lungs. This is where the highest concentration of alcohol is found, as well. This makes it necessary for a suspect to breathe hard into the device when getting tested for alcohol.

However, not every person can blow deeply or sufficiently hard to get accurate BAC readings. Individuals with certain medical conditions or older ones may find it challenging to breathe deeply. For such persons, a blood test will be better for them.

Partition Ratios

Compared to blood tests, breath tests don’t directly give a reading on the BAC levels. The device is designed to measure the amount of alcohol in the lungs. Then a formula is used to convert the amount into a BAC equivalent result. 

The factor used in this conversion is called the partition ratio. This ration is designed to show the relationship of alcohol in the air or breath and that in blood. The law of California sets the ratio at 2,100:1. This shows the quantity of alcohol found in 2,100 milliliters to be equivalent to that found in a milliliter of blood.

The partition ration can result in inaccurate results. Despite the ratio set, each individual has a different rate at which their lungs receive alcohol. As a result, the actual partition ratio varies from one person to the other.

Unfortunately, when a person is facing violations of VEH 23152(b) of driving when their BAC is 0.08% or more, the various ways lungs absorb alcohol will not matter. The measure of the alcohol level and the partition ratio is set as a law. This means when your breath records your BAC results as 0.08% or more using the partition ratio, you will be over the legal limit to drive. Whether or not you are impaired is inconsequential in this case.

Fighting VEH 23152(a) Violations Using the Partition Ratio

Using the partition ratio science, a DUI lawyer can fight DUI charges against their clients. When a person is accused of drunk driving in California under VEH 23152(a), there must be evidence of impairment. The code here requires the driver to have been impaired due to alcohol intake when they drove.

This is an important aspect when a DUI case is at the borderline on BAC results. A person can have their BAC at 0.07% and have committed another traffic violation or failed a sobriety test in the field. This person can also have shown signs of intoxication, making it possible for a DUI conviction to happen.

However, a defendant can have their ratio not at 2,100:1. Due to this, their BAC results will not be at the borderline. With an expert witness, this can be explained to the court and create a reasonable doubt in the case. This can then lead to lesser charges or a dismissal of the charges.

Diets and Medical Conditions with Regard to Breath Tests

A person suffering from some medical conditions or eating certain foods can have their breath trick the breathalyzer. This will automatically result in falsely elevated BAC results. Some of these conditions include:

  • Diabetes
  • Gastrointestinal Reflux Disease and
  • A diet low in carbs and high in proteins

When you have been arrested for a DUI, you must inform your lawyer of any medical conditions you may be suffering from or your diet. The things that may seem unimportant may prove to be essential in your defense.

When you have an experienced lawyer, he or she will investigate to ascertain if your medical condition could result in false BAC results forming a solid defense strategy. Lack of total exposure may result in a wrongful conviction, especially when one was not intoxicated by alcohol.

Gastrointestinal Reflux Disease and Breath Tests

GERD is a chronic condition of the digestive system. It is characterized by acidic refluxes or heartburns that create wrongly elevated BAC results. Individuals suffering from these conditions often have their stomach contents coming back to their mouths. The acids can be interpreted as alcohol by the breathalyzer machine.

Low Carb High Protein Diet and Breath Test

When a person is on a diet that calls for low consumption of carbs and high proteins, their breath can trick a breathalyzer machine. Some of these diets are the Keto or Atkins diets, among others.

These diets are designed to cause a person to burn down stored fats as opposed to glucose for energy. As a result, a byproduct called ketones is created that is equivalent to acetone. Most breathalyzers are not able to differentiate between ethyl alcohol from acetone. Ethyl is the kind of alcohol used in drinks. As a result, the breathalyzer will read ketones as alcohol in a person’s blood.


When a person has diabetes can have elevated BAC results when they take a breath test. The liver of people with diabetes produces ketones that, as earlier discussed, have similar characteristics to alcohol. Individuals who have diabetes find it challenging to produce insulin. This hormone helps burn the glucose from your body as energy, but instead because they burn fats for energy.

When the body burns fats as earlier discussed, it produces ketones that exit the body through breath. The breath for a person with diabetes then fools the breathalyzer machine to giving wrongly elevated BAC results.

Tricking Breathalyzer with Alcohol Residual in the Mouth

After a person has been drinking alcohol, some of it may remain in the mouth lining. This is what constitutes residual alcohol in the mouth. When taking breath tests for a DUI, the individual is asked to breathe hard into the device. This act produces deep air from the lungs that contains alcohol. In the process of blowing, the breath collects the alcohol residual from the mouth that can elevate the readings.

Alcohol residue stays for about fifteen to twenty minutes in the mouth. This means that even when small quantities of alcohol are in your mouth, they get picked and blown into the device. This, in many cases, results in falsely elevated readings.

What Causes Residual Alcohol in the Mouth

Many things can cause your mouth to have alcohol residues. Some of those things include:

  • Alcohol that was consumed recently irrespective of whether it makes the driver drunk according to the law
  • Some medicines such as cough syrups
  • Breath sprays and mouthwashes containing alcohol

Fortunately, alcohol residues in your mouth dissolve in fifteen to twenty minutes. This creates the reason in the Title 17 regulations, why a suspect must be observed continuously for at least fifteen minutes. This period allows for the alcohol in the mouth to dissolve. Also, to prevent the person from taking anything that has alcohol.

Other Contributing Factors to False BAC Readings

With the advancement of technology, the equipment used in breath testing has become increasingly sophisticated. However, there are various factors that under specific circumstances would result in wrong readings. Some of these are:

  • Rising levels of blood alcohol – After one has been drinking, the alcohol levels in the blood continue rising thirty to forty-five minutes after. Sometimes, it can still keep rising for up to two hours. An arrest on a DUI suspicion can happen during this window. This means, at the time the breath test was taken, the alcohol levels may be elevated than when they were driving. With a knowledgeable witness, he or she can testify to this fact and create a doubt about the actual BAC readings.
  • Inhaling chemicals like acetone – This is rare but possible. Individuals that work in places with volatile chemicals like acetone can register elevated BAC readings. When they inhale these chemicals, and they get arrested for suspected drunk driving, the BAC results can be falsely higher than they should be.
  • Interference of the radio frequency – A lot of arguments around this topic exists. In the 1980s, a discovery was made indicating that some devices for breath testing gave unreliable readings because of interference in radiofrequency. If there are devices within the location where the test is being carried out that produce these frequencies, they may interfere with the readings. Such devices include radios, dispatch radios, teletypes, police radar, or handheld transmitters. Newer devices are designed to withstand the interference, it is still possible, and a defense attorney can expertly argue this fact to create a doubt into the results.

Find a Orange County DUI Lawyer Near Me

A conviction for drunk driving comes with severe penalties in addition to other consequences. If you are facing DUI charges due to breath test results, you need to get a lawyer to help you fight these allegations. There are many strategies your lawyer can apply to challenge the readings from a breathalyzer, as discussed above. However, without proper legal representation, one can be wrongly convicted of a DUI offense. At Orange County DUI Defense Lawyer, we have experience in DUI cases and the strategies in challenging breathalyzer results. Call our office today at 714-820-9592, and allow us to defend you.