8 DUI Drug Defenses That Can Get Your Charges Reduced or Dismissed

For those facing DUI charges for drugs, your DUI defense attorney may use any of the following eight defenses to get your DUI charges reduced or dismissed.

1. Lack Of Probable Cause To Stop Your Vehicle

Before a police officer can stop your vehicle, he or she must have probable cause to do so. Probable cause is “reasonable suspicion for a traffic stop”1. This means that you were observed having violated a traffic law, such as speeding, failing to stop completely at a stop sign, or straddling the lanes. In other words, you may not be stopped at random for the purpose of seeing if you have been drinking without some other justification.

The exception to this is at a DUI checkpoint so long as the setup of the checkpoint and how it was conducted conformed to California law. 

Another example of lack of probable cause to stop you is racial profiling. An example is where you are observed driving in an area where there are few African-Americans or Latinos, and an decides to stop you without any other justification other than to inquire why you are driving in an exclusively white neighborhood. 

2. No Evidence You Were Driving The Vehicle

In a situation where an accident has occurred that was not observed by police, an officer might arrive to see several persons standing outside a vehicle. One of these persons, who happens to be the vehicle owner, is showing signs of intoxication. The officer examines the registration and driver’s licenses and asks the owner if he was driving. He denies it but is arrested nonetheless. Because the officer never observed who was driving and no one has admitted to driving, there is no probable cause to arrest you. 

This may not be available to taxi or limo drivers since there would only be one person authorized to drive the vehicle. If a ride-sharing driver is involved and his or her app was on, this may point to the vehicle owner as the only person who could have been driving. 

3. The Vehicle Never Moved

Under California law, the officer must have observed the vehicle to have moved before having the authority to stop, question and then arrest you for DUI. Your vehicle need only move a few inches, even if the engine was not engaged, and the prosecutor can show that you had physical control2.

However, if you are found asleep in your car miles away from any town or happened to pass out in the middle of an intersection, then the officer can reasonably surmise that you drove to that location. Also, if your engine is running, the officer can assume you had just driven or were about to drive. Other indirect or circumstantial evidence of your having driven include:

  • A warm engine
  • Gear is in drive
  • There is a damaged vehicle at scene of an accident
  • The absence of an alternative driver

An adjunct to this is a scenario where you had been in an accident but left the vehicle and the scene and returned home or went to a nearby bar or restaurant where police found you. Unless you admit that you had not ingested any drugs (or alcohol) during the interim between the time you left the vehicle and your being questioned by police, you could just have likely become impaired after you left the scene. 

4. There Is No Evidence You Were Under The Influence Of Drugs While Driving

The most viable defense that you can use if charged with DUID under VC § 23152(f)3 is that the prosecution has insufficient evidence to prove that you were under the influence of a drug while driving. In a DUID case, there are no BAC results demonstrating a quantifiable amount that California law deems as a presumption of impairment. However, you can still be charged and convicted if the prosecution offers sufficient evidence other than any quantity of any particular drug(s) in your system that shows beyond a reasonable doubt that you were driving while under its influence. 

If you were lawfully stopped by an officer for speeding or some other traffic violation, the officer may inquire further as to whether drugs are involved so long as he has a reasonable suspicion that you are under the influence. Classic symptoms of impairment are slurred speech; watery, bloodshot eyes; fumbling with documents; and an inability to understand simple directions or questions. It may be different for drivers under the influence of a drug since different drugs produce different symptoms. 

If marijuana is suspected, for example, your coordination is usually not affected. Few people who smoked or ingested marijuana exhibit slurred speech or have watery, bloodshot eyes, though they may appear glassy. If the officer testifies to this, a defense expert can counter with studies that refute such conclusions in the majority of subjects. 

Field Sobriety Tests

In traffic stops where the officer has observed symptoms of drinking or of ingestion of a drug, the officer may request that you take a series of field sobriety tests that test your coordination and balance. These may include:

  • Walk and turn
  • Stand on one foot
  • Horizontal gaze nystagmus (HGN)

You are under no obligation to take any of these tests and will not be penalized at all if you refuse. However, the majority of defendants are either too fearful of appearing uncooperative, or are unaware that they can refuse to take the tests, and commit to taking them. This includes blowing into a PBT, or preliminary breath test, which only detects the presence of alcohol in your blood. Its results are not admissible as evidence but do provide probable cause to suspect you are under the influence of alcohol. 

The FST tests can be challenged on the basis of the suspect’s physical condition, weather, the terrain where the tests were administered, the nerves and anxiety of the suspect, and his or her level of fatigue. 

One field test designed to indicate the presence of either alcohol or a drug is called the horizontal gaze nystagmus test, or HGN. HGN is an involuntary jerking of the eyeball as the eyes gaze from side to side. Nystagmus occurs when the eye rotates at high peripheral angles. This test must be administered by a DRE, or drug recognition expert, who will take a brief medical history of the suspect, take the person’s temperature, blood pressure, and perform a certain ocular test. This consists of the officer having the subject follow a slow-moving object across his eyes, like a pen or small flashlight. There are 3 indicators of impairment to observe in each eye: 

  • The eye cannot follow the object in a smooth fashion
  • Jerking is distinct and sustained nystagmus when the eye is at maximum deviation
  • The angle of onset of the jerking is prior to 45 degrees of center

So long as at least 4 of these indicators are observed, the officer will testify that the suspect’s BAC was 0.08%. But if marijuana is suspected because the officer detected the distinct odor in the vehicle or found a used joint on the seat or ash tray, then these indicators should not be present. A defense drug expert can testify that studies show that the eyes of a person under the influence of marijuana will smoothly follow the object horizontally and will not deviate before 45 degrees of center. 

If the defendant was suspected of being on a narcotic or a depressant, the person’s eyes should also smoothly follow the pen or flashlight during the HGN test. With a narcotic, the person’s pupils may be constricted. Other symptoms that an officer may miss but which are common for narcotic users are droopy eyes and facial twitching. Challenges to these conclusions can include that an individual’s pupil size is affected by darkness, light, and nervous tension. In some persons, jerking or twitching of the eye is a normal response. 

An officer trying to bolster his conclusion that the defendant was drug impaired may well describe symptoms that are inconsistent with those commonly associated with the suspected drug or the one that a blood test has revealed. This can impugn the officer’s credibility or expertise in assessing a suspect’s impairment and lead the trier of fact to either question any other aspect of his testimony or to disregard it entirely.

5. The Results Of A Blood Test Are Not Evidence Of Impairment

If the arresting officer concludes that there exists sufficient evidence or probable cause to believe you are under the influence of a drug, then you will be asked to take a blood test. If you refuse, you risk suspension of your driver’s license for at least one year with no opportunity to obtain a restricted license before the suspension period ends. Other penalties include increased jail time if convicted among other penalties. 

The presence of a drug in your blood is not conclusive proof that you were under the influence. THC metabolites, found in marijuana, remain in your system from 28 to 45 days. If testing for cocaine, the test will screen for benzoylecgonine, a metabolite of cocaine, that is detectable in your body for several days. Methamphetamine can remain for 2-10 days depending on several factors. In any case, the effects of these drugs would have dissipated long before you drove. 

Also, there is no accepted metabolism rate for a drug as there is for alcohol as it is affected by the person’s age, gender, tolerance, general health, and how the drug was ingested. As a result, no one can testify as to what the drug concentration level was at any time you were driving.

6. The Blood Test Was Not Properly Administered

Any blood test for DUID must be properly administered and follow the guidelines set forth in Title 17 of the California Code of Regulations. Some of the more essential regulations are:

  • The blood draw must be done by an authorized technician
  • No alcohol-based cleaning agent must have been used to sterilize the site where the blood was drawn
  • A sufficient amount of coagulant and preservative must be in the blood vial  
  • The coagulant and preservative must not have expired
  • The coagulant and preservative must have been properly mixed with the sample
  • The sample was properly identified and stored

But even if any of these regulations were not followed, the results of any blood test will not be excluded. Instead, these errors or omissions go to the weight of the evidence4.

7. Your Blood Was Drawn Without Your Consent And Without A Warrant

There are circumstances under which an officer may not draw your blood without your consent or without a warrant. For example, if you were in an accident and left the scene but were found at your home by police, they cannot enter your home without a warrant to arrest you or to force you to submit to a blood test. Similarly, if you are  arrested and taken to a hospital for a blood draw, the officer may not force you to have it drawn absent your consent or a warrant. Obtaining a warrant is relatively easy and quick to do at least in many urban and suburban areas, and there are no exigent circumstances that would obviate the need for, or justify an exception, to the  warrant requirement under the 4th Amendment to the U.S. Constitution5.

Most law enforcement agencies will not seek a warrant to draw your blood in a DUI or DUID misdemeanor matter but are permitted to restrain to forcibly take your blood if you are suspected of a felony DUI and a warrant cannot be quickly obtained. This condition would likely include matters where a felony DUID is suspected. Felony DUID includes an accident where an injury or fatality occurred, you have a prior DUI felony, or you have 3 prior DUI convictions in the past 10-years. 

You also cannot claim you did not give consent if you were unconscious when your blood was drawn6.

8. You Had No Knowledge The Drug Was In Your System

For whatever reason, you may have unknowingly taken a drug, or someone slipped the drug into your food or drink without your knowledge or consent and you became impaired while driving. If you can present evidence to this effect, you should not be convicted of a Driving under the influence of drugs7.

Next Steps If You Need Help

If you have been arrested and would like to learn more about how attorneys charge.

If you want to understand why its important to have an attorney represent you.

If you would like to discuss a pending case with an attorney contact the Aizman Law Firm at 818-351-9555 for a free confidential consultation.

Request A Free Consultation 818-351-9555 


  1. Terry v. Ohio, (1968) 392 U.S. 1, 20 []
  2. Mercer v. Department of Motor Vehicles (1991) 53 Cal.3d 753 []
  3. California Vehicle Code 23152(f) “California’s DUI Drug Law” –  It is unlawful for a person who is under the influence of any drug to drive a vehicle. []
  4. People v. Williams, (2002) 28 Cal.4th 408, 417; People v. Esayian (2003) 112 Cal.App.4th 1031, 1039 []
  5. Missouri v. McNeely (2013) 569 U.S. 141 []
  6. Hughey v. Department of Motor Vehicles (1991) 235 Cal. App.3d 752 []
  7. Vehicle Code 23152(f). []

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