Reasonable or Probable Cause in Los Angeles DUI

  • May 25, 2017

    The general rule is that police officer can only stop a motor vehicle if he or she has a reasonable belief that a crime is being or has been committed. Upon stopping that vehicle, the officer is allowed a brief detention for purposes of an investigation that’s limited in scope. That investigation might include a DUI investigation.

    The initial assessment
    Once a DUI investigation is triggered, the investigating officer will be looking for signs of intoxication or drug impairment for purposes of establishing probable cause for an arrest. While the driver is still in the vehicle, the officer will be assessing him or her for:


    • Bloodshot and watery eyes
    • Slurred speech
    • The odor of an alcoholic beverage or drugs

    Field sobriety testing
    If any of those signs of having consumed alcoholic beverages or drugs are present, the investigating officer will then ask the driver to exit the vehicle. The officer will be carefully observing the driver for any indications of poor balance while exiting. He or she will then ask the driver to perform a series of standard field sobriety tests. Those consist of:

    • The horizontal gaze nystagmus test
    • Walk a straight line and return test
    • The one-legged stand test
    • A breath test using a portable testing device

    These tests are all for purposes of establishing probable cause, making a DUI arrest and taking a person into custody. No matter how authoritative an officer sounds, no law in California requires the subject of a DUI investigation to take field sobriety tests. Be warned that if somebody does agree to take them and fails one or more of them, they’re giving more evidence to a prosecutor to try to convict them on a DUI charge. It’s highly likely that a DUI suspect’s performance of the roadside tests will be video recorded too.

    Breath testing vs. blood testing
    Once a reasonable belief and probable cause are established, it’s highly likely that the driver will be placed under arrest. He or she will be asked to submit to blood alcohol breath testing at the police station. The law doesn’t require the driver to submit to breath testing either, but there will be consequences for refusing. If the arresting officer persists in wanting to determine the blood alcohol content of an arrestee, a search warrant can be sought from a judge. An arrestee’s failure to cooperate with blood testing pursuant to a search warrant will probably result in additional charges.

    Dismissal by motion
    If your opinion is that there was no reason to pull you over or to establish probable cause for a DUI arrest, contact us for a free consultation and case evaluation from a Los Angeles DUI attorney with our law firm. If we believe that the arresting officer lacked a reasonable basis for a traffic stop or probable cause for a DUI arrest, we will likely want to file a motion to quash your arrest and suppress any evidence illegally seized. If that motion is granted, the state wouldn’t have any anything to prosecute you for a DUI with. That’s because any evidence spinning off of an illegal traffic stop, investigation or arrest won’t be allowed into evidence in your case.

    We’re dedicated and aggressive Los Angeles DUI lawyers. Prosecutors, judges and jurors respect us. You deserve the best DUI defense that you can get. Remember that you’re presumed innocent. The prosecution has the burden of proof beyond a reasonable doubt. Hold the prosecution to that burden, and call us for that free consultation right away after any DUI arrest.

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