Using an Expert Witness in a DUI Case
How Can an Expert Witness Help You in Your DUI Case?
If you or a loved one has been charged with driving under the influence (DUI) and the decision to fight the charge has been made, there are two important steps to take: retain a lawyer – preferably an experienced DUI defense attorney – and use an expert witness. The latter often being an underused, overlooked valuable element to winning your case.
But What is an Expert Witness?
An expert witness is a person who is an expert in their field, i.e. they have extensive knowledge, education, skill, training, and experience about their field of interest. In a DUI case, examples of possible expert witnesses include a law enforcement officer or a forensic toxicologist. They can work with your attorney and testify on your behalf in court, often supplying valuable information to the judge or jury hearing your case.
What Can They Do?
Depending on their field of expertise, an expert witness can give their specific opinion with regards to the scientific, medical, and environmental facts and factors that surround your case – with the aim of weakening the prosecution’s case.
A Law Enforcement Officer
This expert has an extensive knowledge about the requirements attached to DUI investigations, including insight into its location and how it is conducted. They can, therefore, identify the errors in the procedure of the officer involved in your case (possibly at the traffic stop), the officer’s investigation itself, or even their conducting of the breath/blood test. Because they know how to do it right, they know how others may fail to do so.
A Forensic Toxicologist
A forensic toxicology expert can give their opinion regarding the clinical pharmacology of the case – the interpretation of the science behind your case. They can elaborate on how that level of alcohol can affect the human body, i.e. whether or not your senses were impaired. They can comment and possibly criticize the way in which your alcohol level was determined, i.e. the Breathalyzer, urine, or blood test, and find reasons why those results were inaccurate. This can include incorrectly calibrated Breathalyzer machines, incorrect use of the machinery, or inexact scientific methods of blood analysis.
For example, the most common blood/alcohol test that is conducted is an enzymatic assay – this means that it does not directly measure the level of alcohol, but instead, it’s by-products from its enzymatic metabolism. This kind of test has an error margin of about 25%!
Field Sobriety Test Expert
Although this may sound like a scam, this person really does exist and can specifically call into question the conditions in which your tests were conducted. They can vouch for unfair road or weather conditions, incoherent or insufficient results, or comment on the administration of the tests.
Accident Reconstruction Expert
If your DUI case involved a car accident, this expert may be called in to help explain the course of events that lead to and included the accident. The reconstruction expert can estimate the speed of the vehicles at the time, when the brakes were applied, whether or not the driver’s reflexes were impaired, and if the intoxication level resulted (directly or indirectly) in the incident.
The Experts’ Testimony
According to Rule 702: Testimony by Experts, the testimony supplied has to be based on sufficient facts or data and must be produced and applied through reliable methods and sound principles by the expert. It will then, as Rule 703 says, be regarded as evidence.
Although an expert witness may not be free or compulsory, they can be very useful. Working together with an experienced attorney and a reliable, knowledgeable expert witness can make a tremendous difference to the outcome of your case.
