Probable Cause for DUI Arrest – Insights from Los Angeles DUI Attorney
Many people assume that police officers can immediately arrest a driver if they notice any signs of alcohol consumption. However, the reality is that many individuals drive after consuming some alcohol, and the mere smell of alcohol, unusual behavior, or the presence of an open container in the car does not automatically justify an arrest. Los Angeles DUI Attorney strongly believes that these factors alone are insufficient to establish probable cause for a lawful DUI arrest.
What Constitutes Probable Cause for a DUI Arrest?
Probable cause typically requires a combination of observable factors, such as:
- The smell of alcohol
- Slurred speech
- Poor coordination
- Other indicators of intoxication
The term “probable cause” originates from the Fourth Amendment of the U.S. Constitution. To establish probable cause, law enforcement must rely on objective and credible evidence—not just the subjective judgment of an officer. The facts and circumstances must be convincing enough that a reasonable person would believe a crime has been committed.
Proper DUI Arrest Procedures
When stopping a vehicle for suspected DUI, police officers must follow legal procedures. The most crucial step is determining probable cause for the arrest, which must be based on concrete evidence rather than an officer’s personal assumptions.
Furthermore, an arrest cannot be based solely on witness statements, even if someone claims the driver has committed, is committing, or may commit a DUI. Without solid factual proof, an arrest may be considered unlawful—something that Los Angeles DUI Attorney frequently challenges in court.
Stages of a DUI Arrest in California
Law enforcement officers generally follow these steps before making a DUI arrest:
1. Pulling Over the Driver
Officers may stop a vehicle if they observe:
- Traffic violations
- Mechanical issues (e.g., broken taillights)
- Signs of impaired driving (e.g., swerving, delayed reactions, erratic braking)
2. Initial Interaction & Observations
- The officer questions the driver and may ask them to step out of the vehicle.
- During this stage, they look for evidence of intoxication or other criminal activity.
3. Identifying Common Signs of Alcohol Intoxication
- Red or watery eyes
- Smell of alcohol on breath
- Disorientation or slurred speech
- Difficulty maintaining balance or using objects for support
- Unusual or erratic behavior
4. Field Sobriety Tests & Preliminary Alcohol Screening (PAS) Test
- The officer may request the driver to perform field sobriety tests or take a preliminary alcohol screening (PAS) test using a handheld breathalyzer.
- At this stage, law enforcement attempts to establish probable cause for a DUI arrest.
- While officers often present the PAS test as mandatory, it is actually optional for most drivers.
- If you agree to take the PAS test, it can later be used against you in court, despite its questionable accuracy.
Important Exception: The PAS test is mandatory if:
- You are under 21 years old
- You are on DUI probation
California DUI Limits
- For drivers over 21, the legal blood alcohol concentration (BAC) limit is 0.08%.
- For underage drivers (under 21), even a BAC of 0.01% can result in an arrest.
Are Field Sobriety Tests & PAS Tests Reliable?
Even if an officer observes signs of intoxication and the driver fails field sobriety tests, this does not automatically provide undeniable evidence for a DUI arrest. Breathalyzer results can be inaccurate, and field sobriety tests are subjective.
Ultimately, an officer may suspect impairment, but the evidence must be strong enough to justify a lawful arrest—a crucial defense that Los Angeles DUI Attorney frequently argues in court.
When Can You Be Lawfully Arrested for DUI?
The only valid reason for a DUI arrest is failing an evidentiary blood or breath test, which measures blood alcohol content (BAC).
Mandatory Testing After Arrest
- If an officer lawfully arrests you for DUI, you are required to take a chemical test (blood or breath).
- Refusing the test after an arrest leads to harsher penalties, including license suspension and increased fines.
Optional Testing Before Arrest
- If you have not yet been arrested and are only under suspicion, you can legally refuse these tests.
Types of Chemical Tests
1. Blood Test
- Law enforcement will take two blood samples:
- One for the state’s examination
- One that you can independently test at a lab of your choice to verify the accuracy of the results.
- When should you take the test?
- If you know you are over the legal limit, do not volunteer for a blood test.
- If you are confident you are under the limit, insist on taking it, as it provides the most accurate BAC measurement and can work in your favor.
2. Breath Test
- This test is conducted at the police station using the Evidential Portable Alcohol System (EPAS).
- Key limitations of the breath test:
- Unlike a blood test, you cannot obtain a second sample to verify the results.
- Certain medical conditions (e.g., lung disease) or even diet can cause false positive readings.
- If you are unconscious or have a medical condition that prevents you from taking the test, you are not required to take it.
Self-Incrimination: The Biggest Mistake
One of the strongest pieces of evidence against you is a verbal confession. If you admit to drinking, you are essentially handing the police an easy reason to arrest you for DUI—even without definitive test results.
Can a DUI Arrest Be Challenged?
A traffic officer can arrest you at any stage of the process. However, if the officer cannot prove to the court that there was probable cause for the arrest, your Los Angeles DUI Attorney can challenge the evidence and seek to have the charges dismissed.
If you or someone you know is facing DUI charges, contact Los Angeles DUI Attorney today to discuss your legal options and build a strong defense.
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