Updated: Nov 21, 2022
Common DUI Defenses And Arguments in California
When you are detained for DUI in California, you will have to fight the DMV's effort to revoke your driver's license and the criminal charges filed by prosecutors. The results of a conviction on these charges are determined by several factors, including whether you have ever been convicted of a DUI or have any criminal convictions on your record.
However, with the assistance of a skilled DUI Attorney, several DUI fines may be reduced or even avoided. It is important to speak with a DUI Attorney as soon as possible after being arrested so that your rights can be asserted.
We'll discuss possible defenses that your DUI Attorney might use for your DUI case. If you haven't been arrested, you can also take some advice on what to do during the moments you are under scrutiny.
Defense #1: Disproving PAS breath test
Almost all DUIs in California are prosecuted under one of two statutes: 23152(b), which states that you had a blood alcohol content (BAC) of .08 percent or higher while driving, and 23152(c), which states that you had a BAC of.08 percent or higher while driving. The most popular of these is 23152(b), and the most common way to measure your BAC is with a breath test system like a PAS.
Your breath test results could seem conclusive—after all, they "prove" how much alcohol was in your bloodstream. However, they aren't always right. There are many reasons why you could get a false positive that "proves" you were over the limit when you weren't. The equipment can be unreliable. The officers administering the test can make errors, and there are many other reasons you might get a false positive that "proves" you were over the limit when you weren't.
The PAS breath test results can never be taken at face value by a good DUI lawyer. Defending your DUI case by questioning the validity of the test results can be quite effective. It's possible that a key piece of evidence against you would be thrown out of the case. It could even result in the charges against you being dismissed.
What makes the PAS different from other breath tests?
PAS stands for Preliminary Alcohol Screening, and it's used at traffic stops to determine whether or not anyone is driving under the influence. The PAS employs a lightweight, compact breath test system that requires little training for officers to operate. It's usually done before you're arrested, usually within minutes of being pulled over. Officers can use the PAS results to determine whether or not to arrest you for DUI.
PAS examinations, on the other hand, are notoriously inaccurate. They have a large margin of error from one sample to the next, unlike the breath screening devices used in police stations and crime laboratories. They're often vulnerable to being deceived by traces of alcohol left in the mouth. Many portable PAS devices lack a "slope detector," which helps screen out this trace alcohol in other breath test machines.
Regardless of the product, the breath test findings may be challenged. However, if you were tested on the side of the road before or after your detention, the gadget was most likely a PAS, which is especially vulnerable to challenge.
What's the big deal about the breath test result?
Prosecutors can seek a DUI arrest with or without a breath test. However, if they have a test that shows the BAC was over the legal limit, which in most situations is.08 percent, it would be much easier to prosecute you. If they don't have this crucial proof (or some equivalent examination, such as a blood test), they'll have to show that the alcohol you drank made you physically or mentally ill. They will need to prove that you were intoxicated at all in some situations.
This is why the results of the tests are so important. Whether or not the prosecutor has breath test evidence will determine whether you are convicted or not.
What if I was actually inebriated? Is it even possible for me to refuse the breath test?
Yes, indeed. It's unusual for a driver arrested for DUI to be completely sober, but it does happen. In certain instances, however, the driver had consumed alcohol—but not to the extent that he or she was a threat to others. It's difficult to reach the "legal cap" of .08% BAC. To surpass it, a grown man may need three or more drinks, whereas a woman may need two or more. You may have even more drinks and still be legally driving if you drink slowly over time or on an empty stomach.
You don't have to show you didn't drink at all in a DUI situation. You simply need to show that your blood alcohol concentration (BAC) was not.08 percent or higher while driving. You don't even have to prove it; all you have to do is raise doubt on whether you were over.08 percent or not.
Even though they were drinking, the test resulted in a number higher than.08 percent, several DUI defendants win their cases. A victory can mean a victory in court, a charge dismissed without a trial, or a charge reduced to something less serious than DUI. The aim is to keep your license, escape prison time, and keep the cost of your DUI as low as possible.
Defense #2:Disproving "Field Sobriety Tests"
FSTs (field sobriety tests) have become a common part of the DUI investigation process. Officers use several physical tests to assess whether you are intoxicated, such as standing on one knee, walking a narrow line, or tracking an object with your eyes. These assessments aren't always accurate, and they're not meant to help you prove your sobriety. They can, however, be used against you as evidence at your trial, and they can be used as grounds for detention.
Fortunately, the flaws with FSTs are well-documented, and their validity can be questioned. This could help you win your DUI case in several situations.
Why Are FSTs Actually Used?
FSTs serve a single purpose: they are basic checks officers use to screen for symptoms of intoxication or drug use. You'll be let go if you "pass," but you'll almost certainly be arrested if you "fail." Isn't this a fair deal?
FSTs, in fact, are one-sided. If an officer asks you to conduct the FSTs, it's either he or she already thinks you're drunk and is searching for a way to show it. There's nothing you can do to "pass" at this stage because the exams are difficult, and everybody can make a mistake at some point. For example, if you're nervous when standing on one leg, it's not because standing on one leg is difficult; it's because you've been drinking, according to the cop. You'll be told you couldn't obey orders if you try to follow the officer's finger with your head instead of your feet, even if the instructions were given instantly, on a windy night, alongside a busy highway.
It's not that FSTs aren't scientifically sound. The officers must adhere to such laws, and the examinations must be conducted in a consistent manner. They have the potential to show drunken actions if done correctly. However, they aren't given to you in a way that allows you to demonstrate your sobriety. Any error counts against you, and the officer who determines whether you "failed" is the same officer who accused you of being inebriated in the first place.
What are the drawbacks of FSTs?
The following are the key issues with FSTs:
They are primarily physical agility assessments. A fit and agile individual would do better on the tests than someone who is out of shape or even perfectly safe but not athletic. This is true in both sobriety and intoxication.
They are more concerned with your ability to obey orders than with your mental state. Since FSTs require you to perform unnatural movements and (basically) exercises you have never performed before, the most important requirement for passing is hearing, understanding, and following the officer's orders. It can be held against you if you make a mistake, misinterpret something, or ask for clarification.
They are carried out in a high-stress setting. Half of the six colleagues would be unable to stand on one leg without losing their balance. Do it at 2 a.m. on gravel with a spotlight shining in your face from a man with a pistol. You've got a recipe for disaster when you throw in a passing semi-truck.
There isn't a grading system in place. You lose if you excel at one FST but fail at another. You fail if you complete four FSTs but fail the final one. There's no way to prove your sobriety or accumulate "successes." It's just a means of gathering evidence against you.
The best recommendation for most drivers accused of DUI in California is respectfully refusing to take the field sobriety tests. You are not expected to conduct them, unlike in some other nations. You would almost certainly be arrested for DUI if you refused, but the officer was most likely planning to arrest you anyway. You're giving him less proof to work with this way.
How can I refute the use of FSTs in my DUI case?
FSTs may be defeated in one of two ways: by filing a motion to remove them entirely as evidence or by simply discrediting them.
A motion is suppressing FSTs. Wherever feasible, this is the best way. To get the FSTs suppressed, a judge must rule that they cannot be used as evidence at all. They're basically off the table. However, this only works if you can prove that the officer did not perform the tests properly in the first place. FSTs, for example, must be done on flat, dry ground; if the defense counsel takes photographs of the location where you were pulled over, demonstrating that it is not level or that it is littered or otherwise obstructed, the judge may order the FSTs to be suppressed. The judge could also remove evidence that the officers did not adequately describe or perform the tests, such as footage of the arrest or statements in the officers' own report.
The FSTs are being falsified. This is the most popular route. The FSTs were conducted "correctly" in many instances, but they aren't solid evidence—for example, you fell or failed in a way that even a sober person might have failed. In this situation, the DUI Attorney will exert pressure on the prosecution by implying that the FSTs will not stand up in court or by outright attacking them in court. FSTs alone may not have a lot of clout with juries.
Many DUI cases never make it to court, so targeting the FSTs is a good way to start. A good DUI lawyer will whittle down the facts, starting with the breath test or blood sample and then moving on to the field sobriety test (FST). Prosecutors will also make a bargain rather than take a case to court if they don't have solid evidence.
Is "Drinking and Driving" an Appropriate DUI Defense?
Most DUI arrests occur shortly after you get behind the wheel, either at a DUI roadblock, the scene of a DUI crash, or during a traffic stop. If the officer learns you are intoxicated or on drugs in these cases, it is clear that you were driving under the influence. But what if the police just question you after you've been arrested? In these situations, "drinking and driving" can be used as a defense to a DUI charge. Consider one of our prescreened California Lawyers in your California Attorney Search.
What is the protection for drinking and driving?
The phrase "drinking after driving" implies that you were sober or under the legal limit while you were driving. You didn't start drinking until after you got out of the taxi. You may have been inebriated when the police discovered you, but you were not inebriated while driving.
This defense is based on two key facts:
It is only illegal to drive while inebriated. Both of California's DUI rules, 23152(b), just make driving illegal while inebriated. It is legal to be inebriated at home, in a parked vehicle, or even on the side of the road (for the purposes of DUI). It is not a DUI if you drink after you have stopped the engine.
Officers have no way of knowing when you began drinking. If police respond to an accident call 15 minutes later and discover you intoxicated or inebriated, they would naturally suspect a DUI. However, this may not be the case. They cannot know whether you were drunk before the crash or if you began drinking again.
Will I face repercussions if I confess to drinking?
It depends on the situation. For example, in Example #3 above, the man may be charged with an Open Container violation for having a flask of whiskey in his car or even Public Drunkenness for drinking on the side of the road. And, even if he didn't realize he struck anyone, the man in Example #1 might be accused of a hit-and-run crime that didn't involve alcohol. However, none of these charges are as serious as a DUI or a DUI Hit and Run.
Underage drinkers are subject to the same rules. If a driver under the age of 21 admits to drinking following an accident or traffic collision, they will face severe consequences. However, the consequences of driving under the influence and under the age of 21 are much more serious.
To put it another way, the "drinking after driving" defense means you're willing to risk a lesser penalty in exchange for avoiding a life-altering DUI.
Is this a viable defense for a DUI involving drugs?
Yes, indeed. The same idea applies to DUI charges involving alcohol, painkillers, or any other substance (legal or illegal): if you can prove you weren't under the influence while driving, you might have a good defense.
However, using the protection of "drugs after driving" comes with the caveat that you must confess to using drugs. Even if you beat your DUI, you would almost certainly face drug charges if you used an illicit drug like crack. However, this is almost always preferable to a drug DUI fee.
What is the strength of this defense? What proof do I require?
Whether or not these defense works is almost entirely determined by the proof you can present. In general, police (and prosecutors) would presume you were driving under the influence if you were found intoxicated immediately after a traffic incident. To make a case for the contrary, you'll need evidence.
The following are some examples of evidence:
Your breath or blood test results indicate a low blood alcohol content, which is consistent with only recently beginning to drink.
Witnesses noticed when you started drinking or saw that you weren't inebriated when you first got out of the car (you'll need strangers for this).
You have receipts that indicate where you bought the alcohol.
The alcohol flask or bottle from which you were drinking was nearly empty, indicating that you hadn't been drinking for too long.
It also helps if you've told the police the same story about your drinking from the beginning. Your claim is more plausible if you simply said, "No, I just started drinking when..." rather than initially denying drinking and then changing your story.
When used correctly, the drinking after driving (or drugged driving) defense can be very effective. It can result in the DUI charge being dismissed without needing a trial.
Defense #3: The Mouth Alcohol Defense
Operating a vehicle with a blood alcohol content (BAC) of.08 percent or higher is considered drunk driving in California. In most cases, law enforcement can use a breath test to measure blood alcohol content (BAC). However, if you've used mouthwash, you may have traces of alcohol in your mouth, which will throw the test off. Even if you are completely sober, you could test positive for more than.08 percent. This is referred to as the "mouth alcohol" defense and is effective in many situations.
Why does mouth alcohol affect breath tests, and how do they work?
Breath tests aren't intended to assess breath taken from the mouth. They're expected to measure "alveolar" air, which comes from deep inside your lungs. This is why you must blow into the system for a long, continuous period of time to get a good sample of deep-lung air. This, in principle, helps the breath test system to determine the percentage of alcohol vapor emitted by blood flowing into and out of the lungs. This is meant to be a clear indicator of your blood alcohol content or how inebriated you are.
The problem is that even though you are not inebriated, other sources of alcohol vapor will interfere with the examination. Consider the scenario where you rinsed your mouth with Listerine, an alcohol-based mouthwash, just before taking the test. If there is still some alcohol in your mouth, it can taste and smell like mouthwash. The alcohol produces vapors that can and will interfere with the test. They can impact the results so much that you tend to "fail" the test (score greater than .08 percent) even though you weren't drinking.
I've heard that breath mints, dentures, cigarettes, etc can cause mouth alcohol. Is this true?
Yes, indeed. Mouth alcohol may come from a variety of places besides mouthwash. This may involve the following:
Breath mints and sprays can contain small quantities of alcohol.
Tobacco chewing, which often includes pure ethyl alcohol
Tinctures, which are herbal medicines combined with a small amount of alcohol, are one form of herbal medicine.
Some cough syrups, particularly those containing alcohol,
Dentures, dental bridges, and dental caps may trap alcohol that has been consumed previously.
After consuming alcohol, you can experience burping or vomiting.
GERD stands for gastroesophageal reflux disease (see our detailed GERD page here)
Other factors, such as a low-carb or ketogenic diet, may mimic the effects of mouth alcohol.
What if I was inebriated? Is it always possible for me to use the mouth alcohol defense?
This is a fairly normal occurrence. It's important to note that having a few drinks and driving isn't always illegal. It is only illegal if your BAC is.08 percent or higher, according to California Vehicle Code 23152(b). Other California DUI laws make it illegal only if the alcohol impairs your driving, such as if you weave or drive recklessly. However, having a small amount of alcohol in your system is insufficient to accuse you of DUI.
That means you could theoretically have had two beers and driven with a BAC of.05 percent and no damage to your driving ability. If you were then stopped and given a breath test, mouth alcohol could result in a false reading.08 percent or higher. To put it another way, the two beers you drank didn't get you drunk; the mouth alcohol did.
Mouth alcohol is often caused by burping after consuming one or more alcoholic beverages rather than by breath mist. You can still use this protection even if you've had a few drinksBefore.
Isn't it true that police search for alcohol in the mouth before administering the test?
Yes, in theory. Prior to administering any DUI breath test in California, officers are required to observe a 15-minute "observation time." This duration of observation is meant to give them enough time to make sure you don't:
Use any breath freshener
Unfortunately, it isn't always effective. For starters, police officers are busy and often distracted by paperwork and other tasks during the "observation time," which means they might not be paying attention to you at all. Second, depending on the source of the mouth alcohol, 15 minutes may not be enough time for it to subside.
Whether or not the police notice you, you can use the mouth alcohol shield.
Do "slope detectors" protect my breath test from the effects of mouth alcohol?
Not all of the time. A slope detector is a system that is attached to certain breath test machines to screen out the effect of mouth alcohol and provide a "pure" reading from deep lung air. Unfortunately, the slope detector is inefficient due to two factors:
An error by the operator
It's possible that the system won't work during your examination, resulting in a false result that the officers mistakenly assume is "clean."
Consequently, even though a slope detector was used, a DUI lawyer could still contest the findings of a breath test.
What evidence do I have that mouth alcohol influenced my breath test? Is it possible for me to win my DUI case?
Depending on the source of the mouth alcohol, you may use a variety of facts. A good DUI lawyer will sit down with you and go through all the potential causes and assist you in putting together a case about what happened. You may use the following evidence:
Receipts for mouthwash/breath spray items or the existence of such products in the police's "inventory scan" of your car.
Receipts from restaurants or bars detailing precisely what you ate or drank before driving
According to eyewitnesses, you used a substance that could trigger mouth alcohol.
According to eyewitness reports, you had heartburn, indigestion, or burping.
Medical records indicate that you have braces, dentures, or dental fixtures or that you have GERD/acid reflux disease.
Your DUI Attorney will also subpoena data from the used breath screening system. The test itself could be called into question if the system doesn't have a slope detector, the detector isn't working, or there is evidence of operator error.
Mouth alcohol is a legal defense that has helped many drivers from being charged with DUI.
Defense #4: Diabetes, a Low-Carb Diet, or "Ketosis" as a DUI Defense in California
If you're pulled over for a DUI, you'll almost certainly be asked to take a breath test. The breath test is intended to determine whether you are legally intoxicated by measuring the amount of alcohol in your bloodstream. However, various factors, such as health conditions and diet, can affect the test's accuracy. People with diabetes, or someone who consumes a low-carb diet, for example, can sometimes be in a condition known as ketosis or ketoacidosis, which may affect their test results. Even if they are sober, they can register as intoxicated.
What is the difference between ketosis and ketoacidosis?
They're the steps your body takes to convert fat into energy. In the bodies of people who follow a low-carb diet, ketosis is a mechanism controlled by insulin. Ketoacidosis is a normal phase that diabetics go through when they don't have enough insulin. For the purposes of this post, we'll refer to both as "ketosis."
Since we get most of our energy from carbohydrates, which break down into glucose (blood sugar) and provide the body with the energy it needs, most people seldom enter ketosis. Some people, on the other hand, do not consume enough carbohydrates or do not have enough insulin, causing the body to turn to fat as a fuel source instead of carbohydrates.
This may include people who:
You have been diagnosed with diabetes
Low-carb diets are recommended, such as low-carb/high-protein, low-carb/high-fat, paleo, and others.
Ketosis would not be achieved for all diabetics or those following these diets. However, if you are breath-checked for DUI, you will almost certainly receive a false reading.
What is the impact of ketosis on a DUI breath test?
When your body is in ketosis, your liver releases ketones, which are a form of a compound. Ketones circulate in the bloodstream in the body. When you blow into a breath test device, small quantities of ketones will be present in your breath, much like alcohol vapor.
Breath testing systems are not as sophisticated as many people believe. They scan your breath for ethyl alcohol using infrared light. Unfortunately, ketones in the breath may be mistaken for alcohol particles, leading the system to overestimate the blood alcohol content (BAC). This can result in an erroneous DUI arrest.
It's important to note that ketones have no intoxicating effect on the body.
What was the best way to tell if I was in ketosis?
An individual must typically consume less than 50 grams of carbohydrate per day to enter ketosis, and many people find that they only need to consume 20 grams or less. This ultimately entails avoiding all grains, starches, and sweeteners. This closely resembles the type of diet that physicians often prescribe to diabetes patients to regulate their blood sugar levels, which is why diabetics may experience false positives on breath tests.
You won't always be able to tell whether you're in ketosis or not. However, there's a chance it's worth looking into if:
You eat a low-carb diet on purpose.
For health purposes, you limit your carb intake.
You ate a lot of carbs on the day of your DUI detention.
You felt sober and were taken aback by your breath test results.
If any of these apply to you, you can speak with your DUI Attorney about the possibility of a ketosis defense.
What if I was inebriated? Is the ketosis defense still valid?
It's possible. You could have been under the legal limit.08 percent BAC even though you had one or two drinks. Even if you were safe to drive, if you had ketones in your bloodstream from carb restriction earlier in the day, the ketones may have driven your test results over the limit.
To use this DUI defense, what proof do I need?
Depending on the circumstances of your case, you can use a variety of facts. Consider the following scenario:
A family doctor's reported diabetes diagnosis
A doctor's comment on the type of diet you were advised to follow
Receipts from restaurants showing what you ate before your DUI arrest
You should keep a food journal or a diet log.
Statements from friends or family members that you eat a low-carb diet on purpose
You don't have to collect any of this information on your own. Your DUI lawyer will help you determine whether the diet is a viable defense in your case and will assist you in gathering the evidence you'll need to prove it.
Defense #5: GERD, Heartburn, or Acid Reflux
GERD is a medical disorder that causes tiny quantities of alcohol from your stomach to be sent back up into your mouth, possibly causing a breath test for DUI to be invalidated. If you have GERD or a similar disorder and your blood alcohol content (BAC) was higher than the legal limit.08 percent, the result may have been inaccurate, and you may not be guilty of DUI.
What is GERD, and how does it impact a breath test for a DUI?
Gastroesophageal Reflux Disease (GERD) is an acronym for Gastroesophageal Reflux Disease. Acid reflux is a disease that affects the stomach and the esophagus, the conduit that connects the mouth to the stomach. If you have GERD, the contents of your stomach can sometimes reflux into your esophagus, a condition known as "reflux." This may happen regularly, infrequently, or just after certain activities, such as consuming a big meal. Heartburn or acid indigestion daily is the most common symptom of GERD.
GERD, on the other hand, is more than just a source of discomfort. Even if you are not legally intoxicated, GERD will cause you to fail a breath test if you are pulled over on suspicion of DUI and given a breath test. If you have a small amount of alcohol in your stomach, reflux will cause vapors from the alcohol to travel up your throat and into your mouth. A breath test can be thrown off by the extra alcohol vapor, making your BAC appear much higher than it really is.
It is possible to beat a DUI charge if you can show that you have GERD and that it could have influenced your breath test.
Can I use the GERD defense if I've had a few drinks?
Yes, indeed. In reality, GERD will only cause breath test results to be thrown off if you have already consumed alcohol. However, it's possible that you consumed such a small amount of alcohol that driving was not prohibited.
Let's say an adult man with GERD eats a big dinner and drinks two small glasses of wine. His BAC could be around.04 percent, based on a rough estimate. It is not illegal for him to drive under California Vehicle Code 23152(b) since the law states that your blood alcohol concentration (BAC) must be at least.08 percent to be convicted of DUI.
However, after feeding, the man develops GERD symptoms such as heartburn. He is sober when he returns home from the restaurant with his wife. They are stopped at a DUI roadblock along the way, and he is asked to take a breath test, which he fails. His BAC is listed as.09 percent on the breath test, which is much higher than it actually is.
GERD has thrown off this man's test results. A DUI lawyer will likely advise him to confess to drinking two glasses of wine and use the GERD argument to argue that he wasn't breaking the law.
What factors are most likely to cause a GERD attack?
Every person with GERD has a different set of triggers. It seems to come on randomly for certain people, who have no idea what causes it. Others experience acid indigestion and reflux due to the following factors:
Having a substantial meal
consuming alcoholic beverages
Spicy food consumption
After being really hungry, you ate.
As you can see, GERD can be triggered by both eating and drinking, making it easy for this disorder to cause a false positive on a breath test.
How can I tell if my GERD had an effect on the results of my DUI breath test?
If you have GERD, your results were almost certainly influenced if:
You puked just before the breath test.
In the days leading up to the exam, you had heartburn.
You burped before or during the exam.
Is it true that officers are expected to look for signs of GERD in DUI suspects before administering a breath test?
Yes, but this protocol isn't always followed to the letter. In principle, police in California can conduct a 15-minute "observation time" before administering a breath test. They're expected to watch for signs of burping or vomiting, which can cause the test to fail. In reality, however, cops are often preoccupied with paperwork and do not pay attention. Many officers are also unaware of GERD and how it can influence the exam. Whether or not the police notice you, you can use GERD protection.
Find A DUI Defense Lawyer in California
1000Attorneys.com is a California Bar Association Certified Lawyer Referral Service that can refer you to a fitting Criminal Defense Lawyer. You will be referred to a DUI Attorney best fit to handle your unique case. You can contact us through our 24/7 live chat (or complete our case details submission form) for a free initial consultation.