Defense of DUI Cases

There are several defenses and strategies that are typically relevant depending on the facts of your case. Not all will apply and we will be able to refine your exact defense as we accomplish more of the tasks in the investigation stage. However, I will describe below some of these strategies.

The DUI prosecutor will point to several factors as evidence that you were drunk driving: poor navigation of your vehicle, an odor of alcohol flowing from the breath, the appearance of being intoxicated, poor performance on the field sobriety test and, of course, the results of the blood or breath alcohol test. Yet each "piece of DUI evidence" is ambiguous, subject to multiple interpretations, unreliable, based on faulty assumptions and open to attack.

Contrary to popular belief, DUI cases do not rest on hard science. They rest on pseudo-science, often times junk science.

Unfortunately, hundreds of innocent people get convicted of DUI every court day, often by pleading guilty even in the face of spurious prosecution evidence. Hopefully, you won't be one of them.

Defense Issues:

1. GERD Or Heartburn Caused A Falsely High Reading On The DUI Breath Alcohol Test

Suffering from Gastroesophageal Reflux Disease (GERD), acid reflux or heartburn can "fool" the DUI breath machines, causing an inaccurately high reading of the blood alcohol level.

The breath machine is supposed to receive and measure alcohol from the deep lung tissue, a region of the lungs called the alveoli. Breath alcohol concentration (BAC) from this "alveolar air" or "deep lung air" is thought to correlate with blood alcohol concentration.

But GERD can cause alcohol to travel from the stomach back to the throat and mouth. When this happens, the DUI suspect blows this "mouth alcohol" (rather than alveolar air alcohol) into the breath machine. The machine then provides a reading higher, often times dramatically higher, than the DUI suspect's true BAC. A person with a true BAC of .05 can read .20.

This problem is not limited to those who suffer from regular or chronic GERD. Anyone who recently ate a large meal, a greasy meal or a spicy meal may experience acid reflux or heartburn. If you take a DUI breath test during this period, the results may be erroneously high.

2. The DUI Police Officer Failed To Read You Your Miranda Rights

Police must advise you of your Miranda Rights in a DUI case if (1) you are in custody and (2) they question you seeking to elicit an incriminating response. If the officers continued to interrogate you after placing you in custody for DUI, and did not first read you your Miranda rights and obtain a valid waiver, then your post-custodial statements will likely be excluded from evidence.

3. Weaving Within Your Lane Does Not Justify A DUI Traffic Stop

Many DUI traffic stops occur because the officer claims to observe the DUI suspect weaving within his/her lane, perhaps with the tires touching the fog line or yellow lane divider, or briefly encroaching into the neighboring lane. Courts have ruled that this usually does NOT justify a DUI traffic stop—unless an "experienced officer" observed "pronounced weaving" for a "substantial distance." If the court finds that your traffic stop was not justified, the entire DUI case will most likely be dismissed.

4. Alcohol On Your Breath Does NOT Mean The Driver Is Under the Influence

In explaining why he believes you were drunk, the DUI officer almost always mentions smelling "a strong odor of alcohol on the suspect's breath." But the officer looks foolish on cross-examination when he admits that alcohol itself (ethanol) has no odor. Rather, it's the mixing agent or flavoring that produces the odor we associate with alcohol. If you doubt this, go to the market and buy a 6-pack of O'Doul's. It tastes and smells just like beer; but it contains no alcohol.

Indeed, laboratory studies show that police officers' perceptions of how strongly a person's breath smells of alcohol simply doesn't correlate with his/her actual blood alcohol level. All that can be gleaned from the "odor of alcohol on the breath" is that a DUI suspect probably consumed some alcohol recently. But it does not provide evidence that the person drank enough to be "under the influence" or to have a BAC .08 or higher.

5. The Officer Lacked Probable Cause For The DUI Arrest

After conducting the roadside DUI investigation, the officer can only arrest you (apply the handcuffs and take you away for a chemical test) if he/she has "probable cause." This means the evidence must rise to a level in which a reasonable DUI officer would believe a crime (drunk driving) has been committed.

You are entitled to a special court proceeding—called a "suppression hearing" or "1538.5 hearing"—in which a judge decides whether the DUI officer had probable cause for the arrest. At the hearing, the officer testifies and is cross-examined by the DUI defense lawyer.

Our firm conducts this hearing routinely in DUI cases. If the judge decides the officer who arrested you for DUI lacked probable cause probable cause, then the subsequent breath or blood alcohol test is excluded from evidence. Often, the entire case is dismissed.

In practice, judges usually side with the prosecution at the suppression hearing, finding that probable cause existed. Still, the hearing provides an invaluable opportunity to question the officer and confront him/her about the problems with the DUI investigation. This often leads the prosecution to reduce the charge or to settle the DUI case on terms more favorable to the defense.

6. There Are Innocent Explanations For Your Faulty Driving

Perhaps the DUI officer saw you swerving for a short distance, make a wide turn or drift out of your lane. Of course he will paint these as sure signs of drunk driving. But in reality, sober drivers engage in these sorts of driving miscues all the time.

How often do you see a car drifting around in its lane, only to look over and notice the driver on the cell phone? Or reading a map? Or eating? Usually, the "bad driving" the DUI officer claims to observe is just as consistent with a distracted or inattentive driver—but otherwise sober driver—as it is with a drunk driver.

7. The Alleged Signs of DUI Are Actually Signs Of Fatigue

Many of the "typical" symptoms associated with DUI can just as easily be explained by fatigue. Sheer exhaustion often causes one to drive his/her vehicle poorly, to have bloodshot and watery eyes, to respond slowly to some of the DUI officer's questions, and to struggle with the field sobriety tests that require vigilance and good coordination.

Obviously, driving while exhausted or drowsy is dangerous, and should be avoided. But the symptoms of driving while exhausted can easily be confused with the symptoms of driving while intoxicated.

8. Your Blood Alcohol Level Was Rising

A DUI suspect can blow a .15 at the police station; but have had a .07 BAC when he got pulled over. Why? Because alcohol takes an average of 50 minutes, but can take as long as three hours, to absorb fully into your bloodstream and create your peak blood alcohol level. This is critical if the DUI traffic stop occurred relatively soon after you finished drinking.

Your BAC was probably still rising. This means that even if your BAC was above .08 when the blood draw or breath test occurred at the police station (or hospital), it may well have been below .08 when you were actually driving. There is no law against having a BAC above .08 at a police station; it's only the blood alcohol level while actually driving that counts for DUI purposes.

9. An Improper 15-Minute Observation Before The Breath Alcohol Test

California regulations require the officer to watch the DUI suspect continuously for at least 15 minutes prior to administering the breath alcohol test. The officer must make sure that during this period the person does not consume anything, burp, belch, hiccup or regurgitate. Any of these may cause alcohol to travel from the stomach to the mouth. Blowing this "mouth alcohol" into the breath machine triggers an inaccurate high BAC reading.

Officers rarely follow this required observation procedure. They usually perform paperwork, write reports, set up the machine and converse with their partners, diverting their attention from the DUI suspect who must be watched vigilantly during this period. Failure to follow this procedure casts doubt on the validity of the test result, and can sometimes get the test thrown out of court altogether.

10. The Police Officer Lacked Justification To Make The DUI Traffic Stop

Police officers cannot pull you over arbitrarily. To conduct a lawful traffic stop, the DUI officer must provide "specific articulable facts" indicating a "reasonable suspicion" that you were committing a traffic violation. You are entitled to a special court proceeding called a "suppression hearing" where a judge determines whether the DUI officer can meet this standard. If he cannot, in all likelihood the entire DUI case will be dismissed.

11. Failure To Comply With California's Title 17 Regulations

California Code of Regulations Title 17 sets forth procedures that must be followed by anyone administering DUI blood or breath alcohol tests. Officers break these regulations all the time in DUI investigations. A failure to follow the regulations can expose the BAC test results to attack, or lead to their exclusion from evidence altogether.

12. Inherent Error Rate In DUI Blood and Breath Alcohol Testing

Let's assume maintenance and calibration of the machines are perfect, the breath or blood test is administered exactly according to procedure, and no background or physiological factors exist that would produce false results (and, by the way, such a "perfect scenario" is rare).

An inherent error still exists as to both blood alcohol testing procedures. Most experts agree the inherent error rate is about +/- .02 for DUI breath testing and +/- .005 for DUI blood testing.

13. The DUI Officer Has No Baseline For Your Performance On The Field Sobriety Tests

The DUI officer will probably claim you "performed poorly" on the field sobriety tests, and that this serves as evidence of impairment. But "poorly" compared to what? This claim means very little without knowing how you would perform normally—even with nothing to drink. People vary tremendously in their natural ability (or inability) to perform DUI field sobriety tests.

How well a given person performs the filed sobriety tests depends on many factors: natural level of coordination and equilibrium, natural level of balance, fitness level, composure in the face of pressure, injuries, age and practice, among others.

14. Factors Other Than Alcohol Can Cause Poor Performance on the Field Sobriety Tests

Even if you performed less than perfectly on the DUI field sobriety tests, this may be attributable to unfair test conditions such as:

  The tests occurring on uneven surfaces or slippery terrain
  The distraction of flashing lights and traffic whizzing by
  The test area being too dark or amidst glaring lights
  Cold temperatures, rain, or wind
  Unsuitable footwear—such as boots, high heels or dress shoes
  Nervousness, anxiety and/or frustration

Most people who had nothing to drink would still struggle with the FSTs under these conditions. The upshot is this: even if you struggled on the roadside tests, this may well be caused by the setting and circumstances rather than you being intoxicated.

15. The DUI Standardized Field Sobriety Tests Were Not Properly Administered

The National Highway Traffic Safety Administration (NHTSA) devised national standards for how DUI officers are to administer the three standardized field sobriety tests: the Horizontal Gaze Nystagmus Test, the Walk-and-Turn Test and the One-Leg Stand Test. But DUI officers often fail to adhere to these national guidelines. Many never even received training as to the NHTSA guidelines. This opens up their whole DUI investigation to attack.

Sometimes a DUI officer will say in his report the DUI suspect "failed" or "performed poorly" on the field sobriety tests; but when the performance is judged according to NHTSA's national standards, the person did everything correctly! This underscores a basic fact of DUI defense: the arresting officers are biased and frequently do slipshod DUI investigations. Their claims and opinions should never be taken at face value.

16. The Non-Standardized Field Sobriety Tests Lack Reliability

The non-standardized field sobriety tests include (among others): the finger-to-nose test, the finger count test, the hand pat test, the coin pickup, the alphabet test, the reverse counting test, and the Rhomberg test (tilting your head back and estimating 30 seconds). The National Highway Traffic Safety Administration (NHTSA) has set no standards for how to administer, score or interpret these tests, and no studies have ever shown them to be reliable indicators of DUI impairment.

17. Field Sobriety Tests Provide a Poor Measure Of DUI Impairment

Even when the standardized field sobriety tests are administered perfectly (which is rare), they still provide a very inaccurate measure of whether a DUI suspect is impaired. According to NHTSA, for example, the one leg stand test has a 65% accuracy rate and the walk-and-turn test a 68% accuracy rate.

This means that if people were convicted based on these roadside tests, one third of them would be innocent and wrongly convicted. Or, viewed another way, when officers arrest DUI suspects based on failing these tests, one in three suspects is wrongfully arrested.

18. Mouth Alcohol Can Contaminate The Breath Alcohol Test Results

Ideally, DUI breath testing devices detect alveolar air of the deep lungs, which is loosely correlated with blood alcohol level. But the breath testing machine can be "tricked" by latent alcohol in the mouth—often caused by burping, belching, or the recent use of cough syrup, cold medicine, mouthwash or breath spray.

When the breath testing machine picks up mouth alcohol rather than deep lung air, it gives BAC readings greatly higher than the true BAC. This becomes a particular problem for DUI arrestees with dentures, denture adhesives, braces, cavities, food impactions, orthodontic work or who have food particles trapped between their teeth (as all of these conditions tend to produce mouth alcohol).

19. Blood-Breath Partition Ratio Is Inaccurate Based on Individual Differences

DUI breath testing assumes that "breath alcohol" accurately reflects blood alcohol based on a 2100-to-1 partition ratio. This assumption rests on the proposition that the average ratio across the population is 2100-to-1. But studies reveal that the ratio of blood to breath varies greatly among individuals.

A DUI suspect with a ratio lower than 2100-to-1 will generate an inaccurately high reading from a breath alcohol test. And there's no way to determine what a given person's ratio is, or what it was at the time of the DUI breath test.

20. The Breath Alcohol Test Yields Unduly High Results During Absorption

Breath alcohol testing while alcohol is still absorbing into your bloodstream often yields falsely high BAC readings. During the absorption stage, which can last as long as three hours after you finish drinking, the BAC in arterial blood is significantly higher—as much as 60% higher—than the BAC in venous blood. Because the alveolar deep-lung air blown into the breath machine is bathed in arterial blood, not venous blood, a falsely high BAC is generated.

21. Police Have No "Special Ability" To Judge Intoxication Levels

Police and DUI prosecutors like to suggest that trained and experienced officers have a "special ability" to discern when a DUI suspect is under the influence (and therefore jurors should defer to the officer's opinion that the DUI defendant was, in fact, impaired).

But a controlled study by Rutgers University's Alcohol Behavior Research Laboratory found otherwise. Police officers' ability to judge intoxication levels was no more accurate than that of bartenders or social drinkers. Moreover, none of the three groups—experienced police officers, bartenders or social drinkers—correctly judged levels of intoxication more than 25 percent of the time.

22. No Sign Of Mental Impairment

Being "under the influence" consists of two types of impairment: mental and physical. Most police will admit that upon being pulled over, the DUI suspect was coherent, alert and responded appropriately to the officer's questions. Therefore no sign of "mental impairment" existed.

But, as any DUI toxicologists will tell you, "mental impairment" always precedes "physical impairment." So if mental impairment was not present, then, presumably, neither mental nor physical impairment was present.

23. Innocent Explanations For The Symptoms Of Intoxication

Police officers almost always claim to have observed certain "objective symptoms of intoxication" in the DUI suspect. The standard list includes:

  Bloodshot and watery eyes
  Slurred speech
  A flushed face
  An unsteady gait

DUI police reports feature pre-printed boxes for these symptoms that officers merely check off. Of course, the officers almost never photograph, videotape or audiotape the DUI suspect so that jurors can later judge for themselves whether and to what extent these symptoms were present.

In any event, non-alcohol causes often explain these observations. For example, fatigue, allergies and eye strain cause bloodshot eyes. Nervousness, embarrassment and anger over the DUI traffic stop cause flushing. Intimidation and fluster cause slurred speech.

The officer rarely takes these innocent explanations into account. The DUI defense attorney must emphasize to the jury that the evidence is just as consistent with non-alcohol explanations as it with intoxication.

24. Speeding Is Not Correlated With DUI

In many of our DUI cases, the officer pulled the client over for speeding. And the officer alleges the client to be under the influence based (at least in part) on the fact the client was speeding. But national studies demonstrate no correlation between speeding and intoxication. A speeding driver is no more likely to be drunk than sober. To be sure, speeding is often unsafe and a violation of the law; but it is not evidence the driver is DUI.

25. Radio Frequency Interference May Have Contaminated Your BAC Tests

Radio waves in the air—known as Radio Frequency Interference (or RFI)—can alter the results of almost any DUI blood or breath alcohol testing device. Radio Frequency Interference can disturb the electronic circuitry of Los Angeles County's Datamaster, San Bernardino County's Draeger Alcotest 7110, gas chromatographs and mass spectrometers, thereby resulting in inaccurate high blood alcohol readings.

Radio Frequency Interference emits from almost any electronic device, including police radios, police scanners, radar devices and computers. Although studies have confirmed the danger of Radio Frequency Interference or electromagnetic interference to render false BAC readings, it is difficult to determine whether or to what extent RFI altered the result in a given DUI case. Yet it is one more reason for skepticism.

26. Breath Testing Machines Mistake Other Chemicals for Alcohol

DUI Breath alcohol testing machines also detect non-alcohol compounds, which they frequently mistake for alcohol. Among the compounds most commonly mistaken for alcohol are ethylene, toluene, nitrous oxide, diethyl ether, acetonitrile and isopropanol.

The presence of any of these compounds in the DUI suspect's lung tissue will likely cause a false, or falsely high, blood alcohol reading. We find that people frequently ingest these compounds at work or in other environments where the chemicals are present.

27. Low-Carb Diets Can Cause Falsely High DUI Breath Test Readings

A DUI suspect on a low-carb diet may generate an erroneously high blood alcohol reading from the DUI breath testing machines. On a high-protein diet, the body produces ketosis as it burns stored body fat for energy (a process that has produced dramatic weight loss for many adherers to Adkins-style diets).

Consumption of carbohydrates (such as alcoholic beverages) during ketosis can cause the body itself to produce a substance called "isopropyl alcohol." Most DUI breath testing machines cannot distinguish "isopropyl alcohol" from ethanol (the alcohol that we drink and that causes impairment).

28. Breathing Techniques May Alter Breath Test Results

Breathing techniques may produce falsely high breath test results. A longer breath sample—more than 10 seconds—may generate a significantly higher BAC reading because the machinery is calibrated to test a 10 second sample. Additionally, a person who breaths shallow or holds her breath may blow residual mouth alcohol, again producing a higher reading than her true BAC. Hyperventilation may also impair the test.

29. Breath Temperature May Alter Breath Test Results

Most DUI breath devices calibrate to test breath at 34 degrees C. Simulator solutions use the same temperature. But when a DUI suspect's breath temperature varies—as is often the case — this can produce a falsely high BAC result. Even a variation only one degree higher can produce a BAC reading 7% higher.

30. A "Disconnect" May Exist Between Your BAC And Symptoms Of Intoxication

Certain symptoms of intoxication can predictably be observed at each successively higher blood alcohol level. Often we see DUI cases where the person's BAC reading comes back very high, two or three times the legal limit.

However, the person's driving, behavior and FSTs are consistent with sobriety or only slight impairment. We know the BAC reading is wrong. It doesn't match the other evidence. We call this a "disconnect case." Any time the alleged blood alcohol level does not match up with the symptoms we would expect to see at that level, the prosecution's whole DUI case is called into question.

31. Blood Tests Have Problems Too

One of the most important concepts to emphasize at a DUI trial where a blood test must be contested is that the alcohol concentration in blood can go up over time because of fermentation. In the same way that the sugar in grapes ferments into wine, the sugar in potatoes ferment into vodka, and the sugar in grains ferments into beer, the sugar in blood - "blood sugar" - can ferment into alcohol. That is why we will have the blood sample re-tested and our lab will test for this phenomenon and check for whether there was an adequate amount of preservatives and anti-coagulant in the test tube.

As noted before, the defense will depend on the facts in your case and not all of the above will apply. I would like to meet with you to go over each of the above issues to develop your personal defense strategy.

Do you have a question for Attorney Cantrell?

Send an email to Attorney Cantrell call 951-784-3200 or contact him here