How to Beat a DUI (and save your license & record)

Tsion Chudnovsky, JD
12 min readMar 5, 2019
Chudnovsky Law

The Definitive Guide on How to Get Out of a DUI

If you have been charged with DUI or DWI, it is key to remember that under U.S. law you are innocent unless 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 lawyers get DUI charges dropped everyday.

But you’re probably wondering:

“Which DUI defenses actually work?”

Here our Los Angeles DUI attorneys review how to beat a DUI case using 20 of the best DUI defense strategies. All based on experience fighting 1000’s of DUI cases.

You can win a DUI case using legal motions, objections and arguments that highlight reasonable doubt or flaws in key evidence required to convict.

While DUI laws vary by state, these defenses apply in California and almost all states.

Let’s dive right in…



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.

Did you know:

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 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 Santa Monica DUI attorney to fight 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.


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.

This is important:

If the officer does not have a reasonable suspicion or probable cause for the stop, your Newport Beach 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 exclude the DUI BAC tests from admissible evidence.

Suppressing key evidence can significantly increase the chances of getting a DUI dismissed since 23152 VC has requirements police must prove with valid, admissible evidence.


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


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.

You may be wondering:

“What do ketones have to do with DUI?”

When ketones are eliminated from our bodies through breath and urine, they convert into alcohol. This mouth alcohol can cause breath testing instruments to read inaccurately high BAC levels.


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 Huntington Beach DUI lawyer can fight to have the blood test results excluded from evidence. Suppressing evidence can win a DUI case since valid proof of at least a .08 BAC is required for DUI conviction under California 23152(b) VC.


“Rising blood alcohol” defenses apply when your BAC level was below legal limits while driving, but then rose above the 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.

You might be wondering:

How do I prove my BAC was below the legal limit?

A rising blood alcohol defense requires using a toxicology expert to examine the results of the BAC test 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.


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


Title 17 of the California Code of Regulations (Title 17), sections 1215–1221 define many specific requirements for DUI blood alcohol tests.

Key Title 17 requirements include:

  1. Technicians must not use an alcohol-based cleaning agent to sterilize the draw site.
  2. Only authorized technicians may perform the blood draw.
  3. The technician must add the correct amount of preservative and anticoagulant in the vial to ensure the sample does not ferment or clot.
  4. The preservative and anticoagulant used must not be expired.
  5. The preservative and anticoagulant must be properly mixed with the blood sample.
  6. The blood sample must be properly refrigerated and stored.

If there are 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.


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


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.

This is key:

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


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:


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 4th Amendment rules requiring probable cause.

Even though Police don’t need probable cause to stop drivers at sobriety checkpoints, they are subject to many strict legal requirements:

  1. The criteria for stopping drivers has to be neutral.
  2. Police should publicly advertise roadblock locations ahead of time.
  3. The time and duration of the sobriety checkpoint should show “good judgement.”
  4. The checkpoint must display sufficient indicia for its official nature to be clear.
  5. Supervising Police officers must make the operational decisions.
  6. Police should detain drivers for a minimal amount of time.
  7. The checkpoint must be in a reasonable location.
  8. Police must take adequate safety precautions.

If Police fail to meet these requirements, a skilled DUI lawyer can challenge any resulting DUI arrest.


Police officers often testify that you exhibited physical signs and symptoms of drinking such as red eyes, slurred speech or an unsteady gait.

But look:

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.


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.

Huntington Beach DUI attorneys can use this disconnect to effectively challenge the evidence and introduce a reasonable doubt about a critical element required to prove guilt.


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.


Police officers typically claim defendants exhibited physical symptoms of being intoxicated such as slurred speech, red or watery eyes or an unsteady gait.

But it is key that:

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 DUI per California 23152(a) 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:


When a defendant is drugged by someone without their knowledge or unknowingly drinks intoxicating alcohol.

For example:

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.


When a person has a valid reason to honestly believe they are not intoxicated.

An example mistake of fact would be if the defendant had provable reasons they thought the impairment effect of a prescription medicine was gone.


When the defendant drives in order to avoid serious injury or death, they are doing so under duress.

For example:

If someone forces an intoxicated person to drive by threat of force, that can be grounds for getting a DUI case 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 in an emergency.

Criminal jury instructions 3403 outline how the accused can be acquitted of DUI if they:

  • Acted in an emergency to prevent significant bodily harm or evil to themselves or another.
  • There was no adequate legal alternative.
  • The DUI did not create a greater danger than the one avoided.
  • The defendant did not substantially contribute to the emergency.

That’s 20 of our best defenses!

If you are wondering how to get out of a DUI in California and want to hire a top DUI defense lawyer, we invite you to call for a Free consultation. No matter how smart you are, it is nearly impossible to fight DUI charges without a lawyer.

We serve clients throughout southern California from our offices in Los Angeles & Orange County and defend clients for all types of DUIs including first DUI charge, second DUI, DUI injury and felony DUI.

Disclaimer: 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. © 2023 Chudnovsky Law. All rights reserved.

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Tsion Chudnovsky, JD

Tsion is founder of @ChudnovskyLaw, a premier California criminal defense and plaintiff’s personal injury law firm.