DUI Investigations
Driving under the influence (DUI) is a serious charge that can carry severe legal, financial, and personal consequences. Many people facing DUI charges have never been in legal trouble before and are unfamiliar with the investigation process that leads to their arrest. Understanding how DUI investigations unfold — from the moment an officer initiates a traffic stop to the point of formal arrest — can help individuals make informed decisions and protect their rights.
Here’s a step-by-step breakdown of what typically happens in a DUI investigation:
The Initial Stop
Most DUI investigations begin with a traffic stop. An officer usually must have reasonable suspicion to pull a driver over. This can be based on:
Observed traffic violations (speeding, weaving, running a red light)
Equipment violations (broken tail lights, expired tags)
Suspicious behavior (delayed starts at lights, erratic braking)
DUI checkpoints (which must follow specific legal guidelines)
At this stage, the officer is not yet conducting a DUI investigation, but they are observing your behavior closely.
Observation and Interaction
Once stopped, the officer will begin to look for signs of impairment, including:
Bloodshot eyes
Slurred speech
The smell of alcohol or marijuana
Difficulty producing license and registration
Confused or inconsistent responses
Even casual conversation can be part of the officer’s assessment. Everything you say and do may be documented and later used as evidence.
Field Sobriety Tests (FSTs)
If the officer suspects impairment, they may ask you to perform field sobriety tests. These are standardized physical and cognitive tests designed to assess coordination, balance, and attention.
Common FSTs include:
Horizontal Gaze Nystagmus Test: Tracking eye movement to detect involuntary jerking.
Walk-and-Turn Test: Following instructions to walk heel-to-toe in a straight line and turn.
One-Leg Stand Test: Balancing on one foot while counting out loud.
Important: You are not legally required to perform field sobriety tests in California. You may politely decline, though refusal may raise suspicion.
Preliminary Alcohol Screening Test (PAS)
The officer may ask you to blow into a handheld breathalyzer at the scene to estimate your blood alcohol content (BAC).
Refusing a preliminary breath test can have consequences depending on your state’s laws, but it is not the same as refusing a post-arrest chemical test.
Arrest
Based on the totality of the officer’s observations—driving behavior, physical signs of impairment, performance on FSTs, and preliminary breath results—they may establish probable cause to arrest you for DUI.
You will usually be handcuffed, read your rights, and transported to a police station or local jail.
Post-Arrest Chemical Test (Evidentiary Breath Test)
Once under arrest, you are typically required to submit to a chemical test of your breath, blood, or urine. Refusing this test can trigger automatic license suspension under "implied consent" laws in most states.
Unlike the PAS test, these results are generally considered more reliable than the PAS test and can significantly impact your case.
What You Should Know
You have the right to remain silent throughout the investigation.
You have the right to speak to an attorney before answering questions post-arrest.
An experienced DUI defense lawyer can evaluate whether the stop and investigation were conducted lawfully and whether evidence can be challenged or excluded.
How an Attorney Can Help
If you've been arrested for DUI, time is critical. A skilled defense attorney can:
Challenge the legality of the traffic stop
Question the administration and validity of field sobriety and chemical tests
Represent you in administrative license hearings
Negotiate with prosecutors or take your case to trial
Every DUI case is unique, and a thorough legal review may uncover issues that can significantly alter the outcome of your case.
As always, if you're facing DUI charges, don't face them alone. Contact the Davis W. Hewitt Law Office for a confidential consultation to discuss your options.
