Defense of DUI
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
31. Blood Tests Have Problems
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.