How to Beat a DUI

The Top 20 Proven DUI Defenses


The Definitive Guide on How to Get Out of a DUI

If you’ve been charged with DUI or DWI, it is key to remember courts are required to presume you’re innocent until prosecutors prove guilt beyond a reasonable doubt.

There are many defenses available to get key evidence tossed out, DUI cases dismissed or charges reduced. This is why the best DUI defense lawyers get DUI charges dropped everyday.

Here we review how to beat a DUI using our top 20 defenses. Although DUI laws vary by state, these defenses apply in almost every state.

Let’s dive right in…


The 20 Best Ways to Beat a DUI [2018]


1. Breathalyzer Test Errors or Inaccuracy

DUI breath tests are the most common blood alcohol concentration (BAC) test. Police breathalyzer tests use small, preliminary alcohol screening devices to screen in the field and large, table-top breathalyzers in the Police station or hospital.

DUI breathalyzers don't measure 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.

However, the actual ratio of tested individuals ranges from 1:1300 to 1:3000 or more depending on: sex, body weight, breathing patterns, body temperature and hematocrit levels (red blood cell ratio).

DUI breath tests are prone to a variety of problems:

  • Physical differences between drivers that affect the partition ratio

  • The device’s margin of error

  • Improper calibration and maintenance

  • Incorrect use by the police officer

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 even “flawless test results” between .08 and .10% because a .02% margin of error could lower the BAC to below the legal .08 alcohol limit.


2. No Probable Cause for the DUI Stop

Police DUI stops must be supported by reasonable suspicion or probable cause. This is because traffic stops are temporary detention by Police and considered a "seizure" under the 4th Amendment.

For DWI stops, the most common reasons Police provide are drivers exhibiting NHTSA driving impairment patterns, 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 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.

 Breathalyzer test and blood alcohol level errors can be a basis for getting a DUI charge dropped or your DUI dismissed.

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. 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 decomposes due to enzymes and bacterial action. Decomposition can create alcohol in the blood.

Blood samples with no alcohol can generate BAC readings of .25 or more, depending on the amount of fermentation. Fermentation can occur if a technician doesn't properly refrigerate the sample or add the correct amount of preservative.

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 limits while driving, but then rose above the .08 California blood alcohol limit by the time Police performed 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.

Key Title 17 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 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. Skilled DUI lawyers know how to get a DUI dropped if BAC test results are excluded.


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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.

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:


12. Improper DUI Sobriety Checkpoint

While some believe sobriety checkpoints are unconstitutional and violate probable cause protections, the California Supreme Court ruled that DUI sobriety checkpoints are legal, administrative inspections similar to airport screenings exempt from the Fourth Amendment rule requiring probable cause to stop a driver.

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:


  • 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 may cause RFI reading errors:

  • Police radios

  • FM and AM radios

  • Microwaves

  • 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 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 a powerful 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.

20. Necessity

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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That’s All 20 Defenses!

If you are looking to hire a top DUI defense lawyer, we invite you to call for a Free consultation. We serve clients throughout southern California from our offices in Los Angeles & Orange County.

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How to Beat a DUI or DWI?

Skilled DUI lawyers have many ways to beat a DUI or DWI by identifying reasonable doubt or legal flaws in key evidence required to convict under VC 23152(b). Inaccurate breathalyzer BAC test results, police report errors, medical conditions and improper police procedure can all get drunk driving charges dismissed.


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:

  • .01% or higher: If you’re under 21 years old.

  • .04% or higher if:

    • You are on DUI probation for a prior DUI conviction,

    • You are driving a passenger for hire vehicle with a passenger (i.e. Uber, Lyft and taxi drivers) effective 7/1/18, or

    • You hold a commercial driver’s license (CDL). This limit applies whether you are driving a personal or commercial vehicle.

  • .08% or higher: If you’re an adult, 21 years of age or older and hold a standard California driver’s license with no restrictions.

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

Last updated 11.8.18


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 case to see if Chudnovsky Law is the best DUI defense attorney for you.