6 Common DUI Defenses in California

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Driving under the influence (DUI) or driving while intoxicated (DWI) can be considered a minor (misdemeanor) or serious crime (felony) in California, depending on the circumstances, such as if it is your first offense or a repeat offense. However, a DUI conviction can bring consequences such as a DMV hearing, license suspension, fines and even jail time. The laws in California on driving under the influence (DUI) are fairly complex, but that opens the door to a cluster of effective DUI defenses. Although an experienced DUI attorney or DUI defense lawyer is the best person to help determine which of these criminal defenses might work best in a particular DUI case, it's a good idea to have a clear understanding of them before a DUI defense is even necessary. Here's an overview of the top defenses to a California DUI charge and how they work.

1. The Defendant Was Not Driving

Being under the influence of alcohol or drugs is not, in and of itself, a crime. Every person who uses over-the-counter cold syrup for a sore throat or drinks a bottle of nice wine with dinner may be considered to be under the influence. But it's only when the person under the influence gets into the car and drives that they may be stopped for a DUI.

To be convicted of a DUI in California, the prosecution must prove both that the person was under the influence AND driving. One proven defense to a California DUI charge is that the person charged with the DUI was, in fact, not driving at all. This usually happens when the police come across someone sitting behind the wheel in a stopped vehicle, sleeping off the effects of alcohol. As long as the vehicle hasn't been, and isn't being operated, by the person under the influence, simply being drunk and in the driver's seat is not enough to get a DUI.

However, if the person drives under the influence, then stops to sleep it off, they may be charged with a DUI. California Vehicle Code Section 40300.5 provides that police can arrest a person if there is probable cause to believe that they have been driving under the influence AND that the person:

  • May cause injury to themselves or damage property unless an immediate arrest is made.
  • May destroy evidence or conceal evidence of the DUI unless an immediate arrest is made.
  • Caused a vehicle accident, vehicle/pedestrian accident, or an incident of any type.
  • Is sitting or lying in a car or other vehicle that is currently blocking a road.
  • Will escape apprehension if the police do not immediately arrest them.

2. Defendant's Bad Driving Was Not a DUI

A person can be charged with a DUI in California for driving under the influence of alcohol or for driving with a blood alcohol concentration (BAC) of 0.08 percent or greater. Even lower legal limits apply to commercial drivers, ride-share drivers and those under 21 years old.

For those charged with driving under the BAC limit, the prosecutor must prove driver impairment. That is, they must prove that the person arrested was driving poorly because of the alcohol they consumed. Since many people charged with DUIs are pulled over for erratic driving behavior, prosecutors often point to that behavior to establish impairment.

One strong defense to this DUI charge is that the bad driving was not related to alcohol or drugs. People who haven't had a drink in their entire lives sometimes may exhibit sloppy or negligent driving. For example, completely sober people may drive through a "pink" stoplight, swerve into another lane of traffic or forget to turn on their headlights from time to time without being under the influence.

This type of defense is particularly strong if the driver otherwise behaved correctly, stopping when the police pulled them over, parking the vehicle without any trouble, and showing no other signs of being under the influence of alcohol or drugs. The fact that the driver had a beer or two earlier in the evening does not convert bad driving into drunk driving.

3. BAC Results Due to Mouth Alcohol

Many California DUI charges are based on Vehicle Code Section 23152(b), that the defendant drove with an over-the-limit BAC as determined by a breathalyzer test. When this happens, defense attorneys sometimes win an acquittal by claiming that the BAC test results were erroneous because they were based on mouth alcohol, rather than on blood alcohol.

It is recognized that alcohol in a person's mouth will throw off the accuracy of a breathalyzer test. The DUI breath testing equipment is supposed to measure alcohol from the person's lungs, but if there is alcohol in a person's mouth, it also gets counted, resulting in a falsely high BAC.

For example, if a person took a swig of whiskey or anything with alcohol in it in the period before taking a breath test, the residual mouth alcohol can impact the BAC result. This includes mouthwash, cough syrup and even stomach alcohol regurgitated in a burp. If the driver imbibed one of these substances, or even alcohol, just before the police stop or the breathalyzer test, this defense can be effective.

4. Officer Failed to Observe for 15 Minutes

Because of the residual mouth alcohol defense, police officers are required to observe drivers for 15 minutes before administering the breathalyzer test to make sure they do not consume anything with alcohol in it and do not belch, burp or regurgitate.

The officer usually remains on the scene for 15 minutes, but many times they do not stand there and actually watch the person for that period of time. If the officer returns to the police car to get the test set up or talks on the radio, they are not observing the driver. This means that the officer did not conduct the investigation according to protocol, that the driver could have burped or used mouthwash during the time the officer wasn't there, and opens the door to a possible DUI defense on that grounds.

5. Breathalyzer Measured Rising BAC

In order for a driver to be prosecuted for having a BAC over the legal limit, the prosecutor must establish that they had a 0.08 percent or higher BAC at the time they were driving. One viable DUI defense to this type of case is that the BAC reflected rising blood alcohol content.

The alcohol a person consumes passes steadily into their blood as they drink. However, it takes 50 minutes to several hours for the BAC to reach peak levels. Until that happens, BAC is said to be on the rise. If a driver was stopped by the police and given a breathalyzer test relatively quickly after having consumed alcohol, an effective argument can be made that the BAC was still on the rise when tested, rendering the breath test results inconclusive.

That means that it may have been under the legal limit during the driver's time behind the wheel, and only increased after the person was no longer driving.

6. Other Causes for Physical Symptoms

Law enforcement may pull you over and even end up arresting you under reasonable suspicion. Many times, a police officer's assessment that a driver is drunk is based on physical symptoms, such as a flushed face, red or watery eyes, and an unsteady gait. These are all listed as objective signs of alcohol intoxication. If combined with a strong smell of alcohol on the driver's breath, the officer is often convinced enough to make the DUI arrest, even without having the driver undergo field sobriety tests.

However, all of these symptoms can have another cause. Anyone with allergies knows that their face can puff up and their eyes become bloodshot, irritated and red. Fatigue can cause an unsteady gait and slurred speech. The fact is, alcohol itself has no smell, while nonalcoholic beer can smell like malt, just like alcoholic beer.

Agile alternative explanations for physical symptoms will go a long way to discrediting the prosecution's case. This can be particularly effective in a case brought for driving under the influence pursuant to Vehicle Code Section 23152(a).