The Handheld Police Breathalyzer Test (PBT) Explained

By: William C. “Bubba” Head, Atlanta DUI Lawyer with 47+ Years of Experience

Clients charged with DUI in Georgia are often confused about why they were asked to blow into a handheld police breathalyzer at the beginning of a traffic stop—only to be handcuffed and later asked to blow into a second, more official device at the station.

This is because Georgia law allows for two types of breath tests during a DUI investigation: the pre-arrest Portable Breath Test (PBT) and the post-arrest Intoxilyzer 9000, used at the police station.

Many people ask, “Why did I have to blow twice?” In this article, veteran Atlanta DUI attorney Bubba Head explains the purpose of each test, how the PBT is used to justify arrests—not convictions, and what really happens during the pre-arrest phase of a Georgia DUI investigation.

Importantly, the roadside PBT is not the same as the cheap breathalyzer gadgets sold online. These police-grade units are calibrated instruments costing $800 to $1,500—and even they aren’t reliable enough to be used as evidence in court.

While some states (like California in the 1990s) experimented with passive alcohol sensors to detect alcohol in the air, Georgia has never approved such tools for law enforcement use.

And keep in mind: even a minor traffic violation or equipment defect—like a broken tail light or tag light—can give police the legal basis to initiate a stop and begin a DUI investigation in Georgia. Here, all traffic offenses are classified as misdemeanors, unlike states that use civil infractions.

What is a Preliminary Breath Test (PBT)?

A PBT device like the Alcosensor FST used in GA is a non-evidential, breath alcohol test. This means that the police officer is limited to reporting that (after the DUI suspect acquiesced to testing) it either showed a “positive” or “negative” reading. The preliminary breathalyzer test, as it’s often known, is a portable, smaller and ‘less sophisticated’ test that police use as ‘probable cause’ to arrest someone they suspect of driving under the influence of alcohol.

Since these roadside screening devices lack the same reliability inspections of the Intoxilyzer 9000, and do not “deliver” a printed result, the alcohol breath test results are not an “evidential” test of your estimated blood alcohol content (BAC).

Bubba Head Set a Legal Precedent: PBT Results Inadmissible in Georgia DUI Cases

In 1996, Bubba Head won a Georgia Court of Appeals decision establishing the legal principle in Georgia that a preliminary breath test “number” cannot be admitted, even at a pre-trial motion hearing.

The Difference Between a PBT and a Breathalyzer

While both breathalyzer tests are administered by law enforcement, they serve very different purposes at different phases of a DUI investigation.

The Portable Breath Test (PBT) is typically offered before arrest, right there at the roadside. Officers use it to help establish probable cause to make a DUI arrest.

The official breathalyzer test—in Georgia, the Intoxilyzer 9000—is conducted after the arrest, usually at the police station or jail. This is the state-administered test that can be used as evidence in court.

Each test also has different legal consequences. Refusing the pre-arrest PBT carries no penalty under Georgia law—it’s entirely voluntary. However, refusing the post-arrest Intoxilyzer 9000 test can trigger an automatic license suspension under Georgia’s Implied Consent Law.

you took the post-arrest Intoxilyzer 9000 breath test and are concerned about how it might affect your case, read how a skilled DUI attorney can challenge and beat breathalyzer results in Georgia.

Should I Take the Police Breathalyzer Test Offered at the Roadside?

No! It is optional, voluntary and IS NOT the official Intoxilyzer that is requested AFTER an arrest for DUI in GA.

Plus, if you “blow” into it, and NO reading is obtained for ethanol (drinking alcohol), most officers will then demand BLOOD from you, in their effort to justify your DUI arrest with a DUI-drugs charge, if something illegal shows up at the GBI.

How Does a PBT Work?

Portable breath machines are not sophisticated instruments, like an infrared spectroscopy device. A simple electrochemical detector, coated on one side of a small “plate,” will react with alcohol molecules in a person’s breath. Using a software algorithm, the fuel cell “counts” the molecules that stick, and then generates a numeric result that is displayed, but is not supposed to be stated or shown on camera. Essentially, the more alcohol molecules that reach the “plate” of the fuel cell, the higher the reading.

All the Georgia preliminary breath test machines use a “fuel cell” to measure positive ions on a small, coated plate about the size of a dime. A narrow, hollow, plastic collection tube leads to the sample chamber, and about 5 seconds of forcible blowing (like trying to inflate a balloon) is all needed to get a “reading.” The objective is to reach your “deep lung air” and get the reading closest to your true blood alcohol content.

The Pre-Arrest Phase of a DUI Investigation: Field Sobriety Tests and the PBT

About 95% of all DUI GA arrests are tied to a moving violation of Georgia traffic laws. Other drivers may be stopped at GA DUI checkpoints near me or sitting or sleeping in a parked car or pickup truck.

Police have been trained on how FIRST to offer a suspected DUI alcohol driver the “field sobriety tests” before offering the preliminary breath test, as outlined per the National Highway Safety Administration (NHTSA) training manual. These three ‘standardized sobriety tests’ are also 100% voluntary. The ‘three-test battery’ comprises the Horizontal Gaze Nystagmus (HGN), the Walk-and-Turn, and the One-Leg-Stand.

Horizontal Gaze Nystagmus (HGN)

When a police officer gives the HGN test, he or she will ask you to follow a pen, finger, or other object with your eyes while the officer moves that object from side to side. The officer is looking for signs of horizontal gaze nystagmus, which is involuntary, rhythmic, jerking of the eyes which can be exacerbated by stress or fatigue. This IS NOT a sign of alcohol impairment, and even registered doctors and nurses don’t use this exam to measure for signs of intoxication.

The Walk-and-Turn (WAT) Test

The Walk-and-Turn, or WAT. Is designed to divide your attention and assess balance, coordination, and the ability to follow instructions—skills supposedly impaired by alcohol.

But here’s the reality: Who actually walks in a straight line, heel-to-toe, for nine steps, with arms stiff at their sides—then turns around in an awkward, unnatural pivot—and walks back another nine steps on that same invisible line?

The One-Leg-Stand

This field sobriety test requires you to balance on one leg, held about six inches off the ground, while keeping your arms tightly at your sides and counting out loud—“one-one-thousand, two-one-thousand, three-one-thousand…”—until you reach 30 seconds.

In a nutshell, these three OPTIONAL and VOLUNTARY roadside screening evaluations should be DECLINED 100% of the time. Why? They are DESIGNED TO FAIL, because the average citizen lacks the balance and physical prowess to complete these considering the unnatural and bogus “scoring method” approved by NHTSA. Briefly, the non-medically trained police officer, who usually has a high school education, lacks enough refinement in “guessing” if you passed or failed.

After the Field Sobriety Tests: The Preliminary Breath Test

Once the person takes (or declines) the field sobriety tests, the officer sees if the driver might be willing to take an Alcosensor PBT (the roadside test, NOT the official breath alcohol test used for state forensic purposes).

A DUI specialist knows the “limitations” of the Georgia-approved portable devices and can cross-examine an officer in a manner to create reasonable doubt of “reliability” of the breathalyzer’s reading. By way of example, a PBT breathalyzer can be calibrated using an aerosol tester, that helps verify that the fuel-cell equipment is displaying accurate readings.

How Police “Add Up” Probable Cause for a DUI Arrest

Police training tells the officer to “add up” these three categories of DUI-DWI investigation:

1. What happened with the VEHICLE IN MOTION (e.g., bad accident, minor accident, making a side turn, changing lanes without a signal);
2. Observations of the driver for SYMPTOMS of possible alcohol or drug use. For alcohol, common manifestations may be red, bloodshot eyes, odor of alcohol on the driver’s breath, an admission of having consumed some alcohol before driving (In Georgia, these police observations alone can lead to a DUI Less Safe charge); and
3. Results of any field sobriety test or tests if the driver foolishly attempts to take them.

Took a Police Breathalyzer at the Roadside? You Can Still Win Your DUI Case

The roadside PBT is not admissible in court — but police use it to justify arrests. Our Atlanta DUI lawyers understand how to challenge the official breath tests and any standardized field sobriety tests that police have used as ‘probable cause.” One of our partners, Cory Yager, was an ex-Roswell and Cobb County police officer, so he understands police tactics and how to dismantle these DUI cases.

Bubba Head is a 47-year veteran Atlanta DUI defense attorney who has authored many legal texts on DUI defense, including 101 Ways to Beat a Drunk Driving Conviction. Larry Kohn is also experienced in criminal defense cases, and has worked for over 30 years defending Georgians involved in DUI cases, criminal matters, and traffic violations.

Our lawyers in Georgia prefer to meet you in person or by video conference. Larry Kohn, Cory Yager (an ex-cop) and Bubba Head are the DUI lawyers near me that have the credentials and experience to help you beat a DUI in the Peach State. We know the expert witnesses needed for trial, like Dr. Spurgeon Cole, retired clinical psychology professor.

Get your FREE PDF copy of Mr. Head’s 430-page book, written for DUI clients.

Call (404) 567-5515 for a FREE DUI lawyer consultation.

Links About DUI Laws in GA and Our Georgia DUI Attorneys:

Alcohol and Drug substance abuse counselor link

Ignition interlock devices, Georgia DDS approved providers

DUI Testing Statute: O.C.G.A. 40-6-392

Main statute: O.C.G.A. 40-6-391

Georgia DUI schools for Risk Reduction DUI classes

Felony Vehicular Homicide: O.C.G.A. 40-3-394

Felony Serious Injury by Vehicle: O.C.G.A. 40-3-394

Links About Administrative License Suspension

Implied Consent Statute: O.C.G.A. 40-5-55

Implied Consent Notice: O.C.G.A. 40-5-67.1

New ignition Interlock Device Statutory Option: O.C.G.A. 40-5-64.1