DUI Defense Guide
Here we review how to beat a DUI arrest using 20 of the most successful DUI defenses.
While California DUI laws are tough on drunk driving, defendants are presumed innocent and prosecutors must prove guilt beyond a reasonable doubt. There are many defense strategies available to get DUI cases dismissed or charges reduced. This is why DUI defense lawyers get DUI charges dropped everyday.
DUI is a technical area of law and DUI cases are rarely hopeless. This guide reviews the best defense strategies our DUI lawyers use including DUI police report errors, BAC blood alcohol content inaccuracy, breathalyzer issues & procedural defenses.
This guide is written for a DUI in California. While DUI laws vary by state, most defense strategies are very similar throughout the United States.
How to Beat a DUI: The 20 Best Ways to Get Out of a DUI
1. Breathalyzer Test Errors or Inaccuracy
DUI breath tests are the most common BAC blood alcohol level test used. Police typically use small testers (preliminary alcohol screening devices) in the field and large, table-top spectrophotometer breathalyzers (evidential breath tests) back in the Police station or hospital. There are several ways that Police breathalyzer test devices can indicate inaccurately high BAC levels.
DUI breathalyzers don't measure blood alcohol concentration (BAC) directly, instead they measure breath alcohol then multiply that by a partition ratio to estimate BAC. Breathalyzers assume a partition ratio of alcohol in your exhaled breath to alcohol in your blood of 1:2100. But the actual ratio of tested individuals ranges from 1:1300 to 1:3000 or more depending on many factors including: sex, body weight, breathing patterns, body temperature and hematocrit levels (red blood cell ratio).
DUI breath tests are inherently prone to a variety of problems:
- Physiological differences between drivers that affect the partition ratio
- The devices inherent margin of error
- Improper calibration and maintenance issues
- Incorrect use by a police officer not following the required test protocol
Even when a DUI BAC test is executed flawlessly, experts agree that chemical testing has an error rate of between .005 to .02%. This allows our Los Angeles DUI attorney to challenge results between .08 and .10% because a .02% margin of error could lower the BAC to below the legal alcohol limit of .08%.
2. No Probable Cause for the DUI Stop
A Police DUI stop must be supported by a reasonable suspicion or probable cause. This is because a traffic stop is temporary detention by Police and considered a "seizure" for the purposes of the 4th Amendment. The officer must have a reasonable articulable suspicion that a crime has occurred to initiate a traffic stop. For DWI stops, the most common reasons are the driver exhibiting NHTSA driving impairment patterns or traffic violations such as speeding or running stop lights.
If the officer does not have a reasonable suspicion or probable cause for the stop, your Orange County DUI lawyer can file a motion to suppress evidence with the court to exclude any evidence obtained by illegal search. This suppression motion or "1538.5 motion" can also exclude the DUI BAC tests from admissible evidence. This is one path for how to get out of a DUI. Suppressed evidence cannot be used against you and usually means the charges must be reduced or the DUI case dismissed altogether.
3. Inaccurate Field Sobriety Test
California's Standardized Field Sobriety Tests (SFST) are not accurate indicators of a driver's impairment. There are only three SFSTs that have actual data to verify their accuracy:
- Horizontal Gaze Nystagmus (77% accurate)
- One Leg Stand (65% accurate)
- Walk and Turn (68% accurate)
And these results are for properly administered tests under ideal conditions, which often is not the case. As anyone who has taken a field sobriety test can attest, they can be hard to pass sober, let alone on the side of a road in the middle of the night. Reasons for innocent test failures can include:
- Poor coordination or non-athleticism
- Nerves and police officer intimidation
- Bad lighting or uneven surface conditions
- Vertigo or poor balance
- Shoes or clothing that interfere with testing
4. Ketosis from Diabetes or Atkins-Style Diets
Conditions such as diabetes, hypoglycemia or low carbohydrate diets (i.e. Paleo or Atkins-style diets) can trigger Ketosis. Ketosis is a normal metabolic process triggered in your body when it doesn't have enough carbohydrates from food for your cells to burn for energy. Without sufficient carbohydrates, your body will burn fat cells instead and produce ketones. For people with diabetes, ketosis is typically a sign of not using enough insulin.
When ketones are eliminated from our bodies through breath and urine, they convert into isopropyl alcohol. This mouth alcohol can cause breath testing instruments to read inaccurately high BAC alcohol readings.
5. Inaccurate DUI Blood Test
Blood testing for alcohol must follow strict protocols to ensure accuracy and there are several ways blood tests can provide inaccurate results. One example is that it is common for blood samples to sit for days before analyzing.
Blood is an organic substance that will decompose due to enzymes and bacterial action. The decomposition process can create alcohol in the blood. For example a blood sample with no alcohol can generate a BAC reading of .25 or higher, depending on the extent of fermentation. If the technician doesn't properly refrigerate the sample or add the correct amount of preservative, fermentation can occur.
Blood tests by law enforcement are presumed by courts to be accurate and the burden is on the defense to prove that they are not. One tool to accomplish that is to file a "blood split motion" to retest the blood and learn details about how the blood sample was stored and the BAC blood test conducted. The most common factors to taint DUI blood testing results are:
- Improper storage of blood sample
- Fermentation of the blood sample
- Contamination of blood samples
If errors are found, your Santa Monica DUI lawyer can work to have the blood test results excluded from evidence. This can get your DUI dismissed since valid proof of at least a .08 BAC is required for DUI conviction under California 23152(b) VC.
6. Rising Blood Alcohol
The "rising blood alcohol" defense is suitable when your BAC level was within legal alcohol limits while you were driving, but then rose to above the .08 California blood alcohol limit by the time Police administered a BAC test.
Rising blood alcohol concentration levels occur because alcohol can take 45 minutes to 3 hours after drinking to become fully absorbed. The peak BAC time after drinking varies widely based on your physiology, when and what you ate, and other factors.
Pursuing a rising blood alcohol defense requires utilizing a toxicology expert to examine the results of the BAC tests and evidence to create a retrograde extrapolation analysis that shows the driver had rising BAC and was below the legal alcohol limit at the time of driving.
A rising blood alcohol concentration defense is most effective when:
- There was a significant delay between being pulled over and when the BAC test is administered.
- Your tested BAC level was close to the California BAC limit, perhaps in the .08 to .11 range.
- You didn't exhibit other clear signs of intoxication such as traffic violations, swerving or slurred speech.
- You were near your destination when stopped so you would not have been DWI.
7. DUI With No Proof of Driving
One of the key elements needed to prove you were driving under the influence is that prosecutors must prove you were driving the vehicle. Proving DUI with no proof of driving can be a challenge for prosecutors:
- If Police found you in a parked car
- If your car was in an accident, but no one saw you actually driving the vehicle DWI
8. Violations of California Title 17
Title 17 of the California Code of Regulations (Title 17), sections 1215-1221 define specific requirements for DUI blood alcohol tests. Some of the key requirements include:
- Technicians must not use an alcohol-based cleaning agent to sterilize the draw site.
- Only authorized technicians may perform the blood draw.
- The technician must add the correct amount of preservative and anticoagulant in the blood vial to ensure the sample does not ferment or clot.
- The preservative and anticoagulant used must not be expired.
- The preservative and anticoagulant must be properly mixed with the blood sample.
- The blood sample must be properly refrigerated and stored.
If there are provable violations of Title 17 requirements, the BAC blood alcohol test results may be excluded or cast into doubt. A skilled DUI lawyer knows how to get a DUI dropped if BAC test results are excluded.
9. DUI Police Report Errors & Misconduct
Police officer misconduct can cause DUI charges to be dismissed or evidence thrown out if Police procedures aren't properly followed, regardless of whether you were driving under the influence or not. Some example issues include:
- Not following California Title 17 requirements
- DUI Police report errors, inaccuracies or missing information
- Fabricated, illegally obtained or manipulated evidence
- Police officer not giving truthful testimony in court
10. Mouth Alcohol
Studies of Breathalyzers have shown that most cannot accurately distinguish readings for ethanol (ethyl alcohol) from other similar methyl group chemical compounds that can be in your mouth. DUI breath testers capture a sample breath of "alveolar air" from deep in your lungs. But equipment can also capture "mouth alcohol" that is not due to drinking alcohol. This causes an alcohol breathalyzer test results accuracy issue because the device can show a high BAC level with little or no actual ethanol in your body.
Mouth alcohol can be caused by:
- Oral medications such as Anbesol, Vicks Formula 44, NyQuil and some cough drops
- Asthma inhaler ingredient Albuterol
- Breath spray and oral herbal tinctures
- Small amounts of alcohol soaked food caught in dental work
- Burping or regurgitating
11. GERD and Medical Conditions
Even the best Breathalyzer DUI breath tests are susceptible to false readings from the following medical conditions that can create mouth alcohol caused by acid traveling from the stomach to the mouth:
- Gastroesophageal Reflux Disease (GERD)
- Hiatal hernia
- Heartburn or acid reflux
12. Improper DUI Sobriety Checkpoint
Are DUI checkpoints legal? While many believe sobriety checkpoints are unconstitutional and violate probable cause protections, the California Supreme Court has ruled that DUI sobriety checkpoints are legal, administrative inspections similar to airport screenings that make them exempt from the Fourth Amendment rule requiring Police officers must have probable cause to stop a driver and pursue a DUI investigation.
Even though Police don't need probable cause to stop drivers at sobriety checkpoints, they are subject to strict legal requirements:
- Criteria for stopping drivers has to be neutral.
- Police should publicly advertise roadblock locations ahead of time.
- The time and duration of the sobriety checkpoint should show "good judgement."
- The checkpoint must display sufficient indicia for its official nature to be clear.
- Supervising Police officers must make the operational decisions.
- Police should detain drivers for a minimal amount of time.
- The checkpoint must be in a reasonable location.
- Police must take adequate safety precautions.
If Police fail to meet these requirements, a skilled Newport Beach DUI lawyer can challenge any resulting DUI arrest.
13. Innocent Reasons for DUI Symptoms
Police officers often testify that you exhibited physical signs and symptoms of drinking such as red eyes, slurred speech or an unsteady gait. These same physical signs can easily have innocent explanations that do not mean you were driving under the influence such as:
DUI SYMPTOM → INNOCENT REASON
- Slurred speech → Fatigue or stress about Police
- Red or watery eyes → Allergy symptoms
- Alcohol odor on breath → Illness, oral medication
- Unsteady gait → Physical injury
- Flushed facial skin → Sunburn or Rosacea
Innocent explanations can help create a reasonable doubt about the physical signs and symptoms.
14. Disconnect Between BAC & Actual Impairment
Sometimes defendants exhibit little to no impairment but tests show a high BAC level. When this disconnect occurs, it is a red flag that perhaps something is wrong with the BAC test results and they cannot be trusted. DUI attorneys can use this disconnect to effectively challenge the evidence and introduce a reasonable doubt about a critical element required to prove guilt.
15. Radio Frequency Interference
Breath test devices utilize electromagnetic and electrochemical technology to detect alcohol contained in a person's breath. These sensitive electronic devices are susceptible to radio frequency interference (RFI) and electromagnetic interference (EMI) that can cause them to indicate erroneously high BAC levels.
Devices that can emit interfering frequencies that could cause breathalyzer devices to produce incorrect readings includes:
- Police radios
- FM and AM radios
- Police radar units
- Cell phones
- Security cameras
Prosecutors are usually quick to point out that a DUI breathalizer may have an RFI detector to refute the presence of radio frequency interference. The problem is, independent expert tests of the detectors have shown they are inaccurate and there are frequency ranges the RFI detectors simply cannot see. When devices emit interfering waves in those frequency bands, the RFI detector will not detect them.
16. Lack of Mental Impairment
Police officers typically claim defendants exhibited physical symptoms of being intoxicated such as slurred speech, red or watery eyes or an unsteady gait. But California DUI laws define both mental and physical impairment. DUI experts have found that impairment from alcohol and drug consumption will always appear first as mental impairment.
So if a Police officer testifies that you exhibited physical impairment, but not mental impairment, DUI defence lawyers can refute the accusation that you were driving under the influence per California 23152(b) VC.
The final four affirmative defenses involve the defendant admitting to DUI, but proving other facts that either excuse or justify the criminal act under California law.
Affirmative defenses are rarely used and the burden of proof is on the defendant. However when the facts support it, the following affirmative defenses can provide an effective defense at trial:
17. Involuntary Intoxication
When a defendant is drugged by someone without their knowledge or unknowingly drinks intoxicating alcohol. An example would be if someone spikes the punchbowl at a party and a defendant gets drunk as a result drinking what they believe to be punch. However, you can generally only claim involuntary intoxication if you did not voluntarily take any intoxicating drugs or alcohol.
18. Mistake of Fact
When a person has a valid reason to honestly believe they are not intoxicated. An example would be if the defendant had provable reasons they thought the impairment effect of a prescription medicine was gone.
19. Duress or Immediate Danger
When the defendant drives in order to avoid serious injury or death, they are doing so under duress. For example, someone forcing an intoxicated person to drive by threat of force can be grounds for getting DUI cases dismissed.
In California the legal defense of “necessity” excuses DUI when a defendant must drive when it is done only to avoid a greater harm. The accused can be acquitted of DUI if they believe that they or another person is in danger or about to be harmed and the only reasonable alternative is to drive. The defendant must be able to prove the necessity to drive in order to avoid a more serious harm than that caused by driving under the influence.
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BAC Chart: Estimated Blood Alcohol Chart
There are many factors that affect a person's blood alcohol concentration (BAC) when drinking. The blood alcohol level charts below estimate the BAC effects of drinking based on the person's: gender, weight and type of drink. Other factors can also affect BAC levels, such as: what food is in your stomach, your liver function and how much water you have consumed.
The California BAC limit for legal driving is:
- 21yo drivers: less than .08%
- Under 21yo drivers: less than .01%
- Commercial drivers: less than .04% (this lower limit applies at all times, even when operating a non-commercial vehicles)
The BAC levels California defined in the charts below are for adults aged 21 years or older that are not commercial license holders:
Note: The data in these California DUI limits charts is from Brad21.org.
Last updated 8.26.18
This information does not constitute legal advice and is not a substitute for individual case consultation and research. No representations are made as to the accuracy of this information and appropriate legal counsel should be consulted before taking any actions. Contact us for a free consultation regarding your specific case and facts and to see if Chudnovsky Law is the best DUI defense attorney for you. Harbor Justice Center.