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Georgia DUI Expert Witness | Criminal Defense Lawyer


By: William C. “Bubba” Head, Criminal Defense Attorney and ABA Board-Certified DUI Attorney

How to Beat a DUI With an Expert Witness

Expert witnesses are “your evidence to the contrary.”

Horizontal Gaze Nystagmus Test Error

Horizontal Gaze Nystagmus Test Error

In most contested driving under the influence cases, a DUI defense lawyer will need to call upon an expert witness to testify. Sometimes this is at a pretrial motion, such as seeking to exclude the horizontal gaze nystagmus test (HGN eye test) from the evidence the jury will later hear. This same expert witness may be needed to testify about an improper field sobriety test administered by the arresting officer, in a DUI trial.

Because most drunk driving or drugged driving cases will have some sort of forensic test (e.g., breath alcohol test, DUI blood test, urine test), challenges to the methodology used, the forensic reliability, chain of custody, contamination of sample issues, and medical conditions that can cause a false positive (additive) reading or erroneous reading from an endogenous chemical produced in ketoacidosis, that is emitted from the breath.

For example, extensive medical studies have been conducted at the University of Washington in Seattle, on lung physiology, from breath alcohol testing, and the phenomenon of alcohol molecules being “picked up” from mucous membranes.

Expert Witness Definition

An expert witness is a person who has specialized educational training, on-the-job experience, and/or a work history that enables him or her to know or possess advanced-level information that exceeds what the average man or woman knows. For example, the character played by Marisa Tomei in the movie “My Cousin Vinny” possessed knowledge and expertise in the area of general automotive mechanics that were far beyond the knowledge of the average layperson. This allowed her to be offered as an expert witness.

The best expert witness is someone whose extensive training and experience cannot be challenged by the prosecutor. The more the State’s lawyer attacks the expert, the more damage is done to the Prosecution’s criminal case. Again, think of the prosecutor asking her about setting the proper timing on a 327-cubic-inch engine in a 1957 Chevy.

Jurors almost always can understand the top forensic science experts, since these professionals are great teachers, and can bring the concepts and principles to jurors in a way that the jury comprehends. This is what makes an expert witness so valuable.

How to Get Out of a DUI By Using Experts

No matter how experienced your DUI lawyer may be, he or she cannot TESTIFY at your trial. It is very rare that a DUI attorney defending you at trial will not NEED an expert witness, or even two or more. This is because the State will make out its case, for the jury or the Judge (in a bench trial), and that evidence — if not REFUTED — usually gives the victory to the State.

Once the State “rests,” which signifies that they are satisfied that they have put up enough evidence to get a DUI conviction, the burden shifts to the Defense, to carry its burden to neutralize or disprove what the State witness or witnesses offered. By bringing in your experts, you bring in “evidence to the contrary,” and (hopefully provide the jury with “reasonable doubt.”

What is an Expert Witness?

DUI Blood TestEvery driving while intoxicated case has one or more “fact witnesses” from the Prosecutor. These witnesses always include the police officer who was arrested, plus any other officers or crime lab workers needed to lay a foundation for the blood, breath, or urine tests, or possibly other people who witnessed an accident. These are called “lay witnesses,” as DUI attorneys call them. But, some crime lab people talk about both facts and as an expert, about laboratory testing methods.

These people are there to talk about what they did, what they observed, their impressions, and (often) their opinion about the accused person’s “sobriety,” based upon specific things they observed. So, what makes an expert witness, and how is that person’s testimony different?


Expert Witness Testimony

In DUI defense, a skilled drunk driving attorney’s expert witness database may include:

  • A medical expert witness who can explain that the accused drunk driver’s poor balance is due to a pre-existing condition like prior concussion, vertigo or an inner-ear disease;
  • A forensic laboratory expert witness who can explain that the state crime laboratory’s shoddy quality assurance protocols fall short of proving blood alcohol calculator reports;
  • Former state police academy trainers or experts in “testing and measurement” who can explain how the field sobriety tests were botched;
  • Scientists or ex-law enforcement officers who have received factory training or an expert with a computer science background sufficient to explain how and why a breathalyzer can malfunction;
  • In a DUI Drugs case, a Ph.D. pharmacologist or medical doctor who can describe and identify that the driver was taking medication within the prescribed limits;
  • A nurse expert witness or an EMT at a car accident scene, who explains the Glasgow Coma scale, for the person being oriented or disoriented;
  • An orthopedic expert witness identifying an accused’s club foot, reconstructive surgery, or serious prior surgery that would limit a person’s ability to perform field sobriety tests.

Typical Expert Witness Fees

Expert witness fees are paid by each client, beyond the cost of a DUI lawyer. Because the best DUI experts are in high demand by drunk driving defense lawyers, expert witness services, plus their travel costs and accommodation costs do not come cheap.

In cases with a DUI per se test for a BAC level that is over the “legal alcohol level,” very few trial victories will be accomplished without a DUI defense expert to totally refute or poke holes in the police officer’s procedures, or the breath alcohol machine maintenance records and reliability. Similarly, most citizens who have been exposed to television “reality” shows involving DUI field sobriety tests believe that what they are watching the police officer does is “real science,” and it is NOT. An expert is needed to show how unreliable the field tests really are.

Standardized Field Sobriety Test Unscientific

Unscientific Standardized Field Sobriety Test

If your DUI case involves a breath or blood test, it will be critical that an expert is enlisted to testify to the unreliability of these chemical tests and point to any potential flaws in your test results. This fee should be included in the cost of a DUI quoted to you by an experienced criminal defense attorney. You can have the best DUI lawyer in America, but without an expert witness or two, the defense case will now go very far. By way of analogy, you can buy the latest, fully loaded Rolls-Royce, but without gasoline, the big-ticket vehicle will not go far.

What Kind of Attorney Do I Need? Searching for The Best DUI Lawyer

After being arrested for DUI in Georgia, the first thing to do is identify an expert on Georgia DUI law through top attorney ratings. Look at who is BEHIND the law firm, review each of the trial lawyers’ credentials, and check out the criminal defense attorney who leads the law office. Every experienced DUI lawyer in the law firm must have full command of DUI laws and possess training in all aspects of successfully challenging the driving under the influence criminal case.

This successful defense record must include suppressing breath alcohol tests, and knowing every prior appellate decision on the Georgia implied consent law. An increasing number of drugged driving cases require that our criminal defense lawyers know how to challenge a GBI blood alcohol or drugs test. Being an INSTRUCTOR in the three NHTSA standardized field sobriety tests (SFST) is also necessary.

The best DUI attorneys in Atlanta, Georgia will offer you a FREE consultation, explain how their criminal attorneys search for a successful defense in your case, and aggressively represent clients to the maximum extent the law allows. Limit your search to DUI lawyers who have legitimate lawyer ratings and a history of proven results on knowing how to beat a DUI. If we are the criminal defense attorneys for you, ask us about our attorney payment plans.

Call our DUI defense lawyers NOW, 24-7, for an initial case review and FREE legal advice: 404-567-5515, or email our criminal justice attorneys.


Other valuable insights on this website:

When Is a DUI a Felony in Georgia?

Georgia Hit and Run Laws

Dui License Suspension
How Much Jail Time for a Dui Warrant

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