If you were recently stopped or arrested for DUI in Gilbert, you may be wondering how the investigation actually works — and whether the police followed proper procedures. Arizona aggressively prosecutes DUI offenses, but law enforcement must still follow strict constitutional and statutory requirements.

Understanding how DUI investigations unfold can help you identify potential defenses and protect your rights.

At Guardian Law, we represent individuals throughout Gilbert and Maricopa County facing serious criminal allegations, including misdemeanor and felony DUI charges. Early legal intervention often makes a critical difference.

Step 1: The Initial Traffic Stop

Every DUI case begins with a stop. Police must have reasonable suspicion that a traffic violation or criminal offense occurred.

Common reasons for DUI stops in Gilbert include:

• Speeding or unsafe lane changes
• Failure to maintain a lane
• Equipment violations
• Running a red light or stop sign
• Responding to an accident

If the stop was not legally justified, any evidence obtained afterward may be subject to challenge.

Step 2: Officer Observations

Once the vehicle is stopped, the officer begins observing the driver for signs of impairment, such as:

• Odor of alcohol
• Slurred speech
• Bloodshot or watery eyes
• Fumbling with documents
• Confusion or delayed responses

Under A.R.S. § 28-1381(A)(1), a person can be charged if impaired “to the slightest degree.” This is a low legal threshold, which is why officer observations often play a central role in prosecution.

Body camera footage frequently becomes key evidence in these cases.

Step 3: Field Sobriety Tests (FSTs)

If the officer suspects impairment, they may ask you to perform standardized field sobriety tests, including:

• Horizontal Gaze Nystagmus (eye test)
• Walk-and-turn
• One-leg stand

These tests are designed to assess coordination and divided attention.

Important to know:

• Field sobriety tests are voluntary.
• Performance can be affected by medical conditions, fatigue, nerves, or uneven surfaces.

Prosecutors often rely heavily on these results, but they are not scientific measurements of BAC.

Step 4: Preliminary Breath Test

An officer may request a roadside preliminary breath test (PBT). This device provides an estimate of blood alcohol concentration but is generally used to establish probable cause for arrest.

Unlike post-arrest chemical tests, roadside PBT results are often not admissible to prove guilt at trial — though they can justify the arrest decision.

Step 5: Arrest and Chemical Testing

If the officer believes probable cause exists, you will be placed under arrest.

After arrest, law enforcement typically requests a formal breath or blood test. Arizona has an implied consent law, meaning that by driving, you agree to submit to testing if lawfully arrested for DUI.

Refusal can result in:

• Automatic license suspension
• Use of refusal as evidence
• A possible search warrant for a blood draw

Blood tests are common in Gilbert DUI investigations and are sent to a crime lab for analysis.

Step 6: Administrative License Suspension

Separate from the criminal case, the Arizona Motor Vehicle Division (MVD) handles license consequences.

If your BAC was 0.08% or higher — or you refused testing — you generally have 15 days to request an MVD hearing. If you do not act, your suspension automatically begins.

This administrative process is independent of the court case.

Step 7: Charging Decisions

DUI charges in Gilbert may include:

• Standard DUI (A.R.S. § 28-1381)
• Extreme DUI (A.R.S. § 28-1382)
• Super Extreme DUI
• Aggravated DUI (A.R.S. § 28-1383), a felony

Aggravated DUI applies in cases involving:

• Multiple prior DUIs within 84 months
• Driving on a suspended or revoked license
• A child under 15 in the vehicle
• Required ignition interlock violations

Felony DUI investigations often receive heightened scrutiny and may involve additional record checks.

Common Defense Issues in Gilbert DUI Cases

An experienced criminal defense attorney in Arizona will carefully review:

• Whether the initial stop was lawful
• Whether probable cause supported the arrest
• Whether field sobriety tests were administered correctly
• Calibration and maintenance records of breath devices
• Chain of custody for blood samples
• Timing of the test within the two-hour statutory window
• Constitutional search and seizure issues

DUI cases frequently turn on technical and procedural details.

Frequently Asked Questions

Can I refuse field sobriety tests in Arizona?

Yes. Field sobriety tests are generally voluntary. However, refusal may still lead to arrest if other signs of impairment exist.

What happens if I refused a breath or blood test?

Refusal typically results in an automatic license suspension and may trigger a search warrant for a blood draw.

Are DUI investigations recorded?

Most DUI stops in Gilbert are recorded on body cameras and sometimes dash cameras. This footage can be critical evidence.

Can DUI charges be dismissed?

Every case is unique. If law enforcement violated constitutional procedures or failed to follow proper testing protocols, it may significantly impact the case.

Protect Yourself Early

A DUI investigation is built step by step — from the traffic stop to chemical testing. If any link in that chain is flawed, it can affect the prosecution’s case.

At Guardian Law, we conduct detailed case analysis, examine police reports and video evidence, and aggressively challenge weaknesses in the State’s case. We represent clients in Gilbert, Mesa, Chandler, Phoenix, Scottsdale, and throughout Maricopa County.

Call Guardian Law today at (602) 888-8020 for a confidential consultation.