A driving under the influence charge is tough to dispute. Prosecutors offer “scientific” evidence to jurors, and jurors tend to trust “science.”

If you are charged with DUI, how can you overcome the presumption that the evidence against you is scientific?

In many DUI cases in this state, the questionable “science” behind field sobriety tests, breathalyzers, and blood tests must be challenged in court by a DUI expert witness who can explain why these tests are inherently flawed.

WHO ARE EXPERT WITNESSES AND WHAT DO THEY OFFER?

Generally speaking, in criminal and personal injury cases, witnesses who are considered “experts” are allowed to provide technical or scientific details, insights, and explanations that may not be familiar to most judges, jurors, defendants, or attorneys.

Criminal defense lawyers routinely work with authorities who may testify as experts in criminal cases: toxicologists, accident reconstruction experts, ballistics experts, civil engineers, medical examiners, and other professionals who may give expert testimony in a criminal proceeding.

HOW IS AN EXPERT’S TESTIMONY TREATED DIFFERENTLY?

How is the testimony of an expert different from the testimony of what is called a “lay” witness?

A “lay” witness in a criminal case typically has a direct, personal connection to the case. In a DUI trial, lay witnesses can include eyewitnesses, victims, and arresting officers.

When a lay witness testifies in a criminal case, it is from direct personal knowledge. An expert witness, however, has no personal stake or connection to the case.

The presumed objectivity of expert testimony makes it persuasive – and in many cases makes it a key part of a DUI defense strategy.

HOW IMPORTANT CAN EXPERT TESTIMONY BE IN A DUI CASE?

In DUI cases, an expert witness is usually someone with special training or experience in medicine or psychology. That training or experience is presumed to make the expert an authoritative witness.

In many DUI trials, the testimony of an expert witness is what makes the difference between a conviction and an acquittal or a dismissal of the charge.

In some cases, a defendant’s not guilty plea can be considerably strengthened by a favorable statement or testimony from an expert witness.

Not every DUI case will require expert testimony. Depending on the circumstances of your arrest and the details in the charge, your DUI lawyer will help you decide if expert testimony should be sought for your defense.

WHAT MAKES A WITNESS AN EXPERT?

Exactly what makes a particular witness an expert? The law is silent on the matter, and in the end, what defines an expert is subjective. Most witnesses who are considered experts will have some or all of these generally-accepted indications of expertise:

1. considerable research, educational, and professional experience
2. research and articles published by professional journals
3. academic awards, credentials, and post-graduate degrees
4. prior recognition and experience testifying as an expert

WHAT EXPERTS TYPICALLY TESTIFY IN DUI CASES?

The defense in a California DUI trial will typically seek testimony from one or more of these experts:

1. A field sobriety test (FST) expert can offer reasons why a defendant’s poor balance may be caused by a medical condition and not by intoxication. Someone with a Ph.D. in clinical psychology can explain how FSTs lack rigorous scientific reliability.

2. A breathalyzer expert might be an electrical, mechanical, or software engineer or an ex-police officer with comprehensive breathalyzer training and experience. Breathalyzers can malfunction. Certain foods and medical conditions can cause false readings.

3. Former police officers and police academy instructors can explain from personal experience how FSTs, breath tests, and blood tests are frequently misconducted by police officers and generally misunderstood by the public at large.

4. When the DUI charge is for driving under the influence of a drug or substance other than alcohol, a pharmacology expert’s testimony may be necessary to refute the charge.

5. A forensic laboratory expert can explain how crime labs fail to meet rigorous standards and how blood and urine samples are frequently mishandled and contaminated.

ARE EXPERTS WORTH THE COST?

If you are charged with DUI in southern California, and if you and your DUI defense lawyer jointly determine that an expert witness will be necessary for your defense, you will have to make a critical decision: Is your desired expert witness worth the cost?

Expert witnesses expect to be well-paid for their time and expertise.

Have a frank, candid, and upfront discussion with your defense lawyer about the cost and the necessity of an expert witness. It is always best to go with your DUI attorney’s recommendation, so be certain that you understand all of the fees and the fee arrangement.

WHAT SHOULD YOU ASK YOUR DUI ATTORNEY?

In fact, if you are facing a DUI charge, ask your attorney as many questions as necessary. Raise any and all of your concerns.

It will be important for you to understand every aspect of both your case and your relationship with your DUI attorney.

Again, not every DUI case will require expert testimony.

For example, if your DUI is a first offense with no aggravating circumstances, but if the evidence against you is conclusive and a conviction is certain, your attorney may recommend accepting a plea bargain and avoiding a trial entirely.

Every DUI case is different and unique. That is why you must have the advice and representation of an experienced Orange County DUI lawyer if you face a DUI charge – now or in the future – here in southern California.

WILL YOU NEED AN EXPERT TO TESTIFY ON YOUR BEHALF?

Research is always being conducted – at universities and research facilities around the world – regarding intoxication and its relationship to driving.

Every year, lawmakers in almost every state find some “scientific” reason to tweak the DUI laws and make them just a bit more harsh and complicated.

As DUI laws and DUI cases grow in complexity, the number of DUI defendants who need the help of an expert witness is certain to increase.

If you are charged with DUI in California, your DUI defense attorney will know if an expert witness is needed in your case. Contact that attorney as soon as you can after a DUI arrest, and follow your attorney’s advice.

Your freedom and your future will depend on it.