The HGN Test: How It Can Make or Break Your DUI Case

If you’ve been pulled over under suspicion of DUI, the Horizontal Gaze Nystagmus (HGN) test might be one of the first field sobriety tests an officer administers. But what many professionals don’t realize is that this test is far from foolproof—and a failed HGN test could put your career, reputation, and future at serious risk. If you’re facing DUI or other criminal charges, time is critical. Call The Law Office of Joshua A. Lopez, LLC at today to start building your defense.

What Is the HGN Test?

The HGN test is designed to detect involuntary eye movements (nystagmus) that become more pronounced under the influence of alcohol. During this test, an officer moves a small object—usually a pen or flashlight—side to side while observing your eye movements. If your eyes jerk at certain angles, the officer may interpret it as a sign of impairment.

Vertical HGN: A Sign of Severe Impairment?

Vertical Gaze Nystagmus (VGN) is a lesser-known but equally significant test officers may use during a DUI stop. Unlike HGN, which detects eye movements from side to side, VGN examines involuntary jerking when the eyes move up and down. Law enforcement often associates VGN with higher levels of intoxication or the presence of certain drugs. However, like HGN, VGN can also be caused by medical conditions, fatigue, or incorrect administration by an officer.

The Problem With the HGN Test

While officers rely heavily on HGN results, the test has significant flaws:

• Medical Conditions & Medications: Nystagmus can be caused by fatigue, neurological conditions, or even prescription medications.
• Improper Administration: Many officers lack proper training, and if they don’t follow standardized procedures, the results can be skewed.
• Subjectivity: Unlike a breathalyzer or blood test, HGN results are based solely on the officer’s observations, which can be influenced by bias or environmental conditions.

If you failed an HGN test, that doesn’t mean you’re guilty. DUI charges can often be challenged based on improper test administration or other factors. You need an experienced criminal defense attorney who knows how to attack the prosecution’s evidence.

Why Professionals Can’t Afford a DUI Conviction

For professionals like nurses, doctors, teachers, pilots, and commercial drivers, a DUI charge can mean more than just fines and jail time—it could cost you your license, job, or even your entire career. Arizona law is strict, and without the right defense, you could face:

• Up to six months in jail
• fines and fees up to $3,500
• License suspension
• A permanent criminal record

More Than Just DUI: Other Charges That Could Ruin Your Career

DUI isn’t the only charge that can threaten your livelihood. I defend professionals facing:

• Jail Time – Up to six months in jail
• Fines & Fees – Up to $3,500
• License Suspension – Possible suspension of driving privileges
• Criminal Record – A permanent mark on your record

Act Fast: Your Defense Starts NOW

If you’re facing a DUI or any other criminal charge, you need to act immediately. Prosecutors are already building their case against you. The sooner you get legal representation, the better your chances of beating the charges.

At The Law Office of Joshua A. Lopez, LLC, I fight aggressively to protect your rights, your career, and your future. Call me today at for a free consultation. Don’t wait until it’s too late—your livelihood is on the line.