If you’ve been charged with a crime, your defense attorney may use an expert witness to assist with your defense strategy. While many criminal cases hinge upon technicalities and scientific issues that may be difficult to convey to a jury, the role of an expert witness can be crucial. They can help the court understand the evidence, challenge the prosecution’s case, weigh the reliability of witness testimonies, and reduce the risk that you will be wrongfully convicted.
What Makes Someone an Expert Witness?
An expert witness is one who is qualified to testify about a specific subject matter based on their expertise, education, and experience. But just because someone knows a lot about a topic doesn’t necessarily qualify them as an expert — their knowledge must be above that of a layperson. Although a layperson can testify about facts or things that they have observed, an expert must have certain training about a fact or piece of evidence at issue in order to testify. If an expert does not have the necessary credentials or relevant knowledge, a judge might not permit them to testify in the case.
Under Oklahoma law, an expert may testify their opinion in a criminal case if they meet the following criteria:
- Their testimony is based on sufficient facts or data
- Their testimony is the product of reliable principles and methods
- They have applied the principles and methods reliably to the facts of the case
The facts or data the expert bases their opinion on may be made known to them before or during the hearing. They may testify their inference without providing previous disclosure of the underlying facts, unless the court requires it. Importantly, an expert witness may be used in criminal cases at both the state and federal levels.
Types of Expert Witnesses
There are a wide array of expert witnesses who can bring their knowledge into a criminal case. For instance, if the prosecution is relying on DNA to prove your guilt beyond a reasonable doubt, a DNA expert’s testimony can call it into question. Depending on the facts, expert witnesses may also be used to challenge other evidence in your case, such as blood spatter, firearms, weapons, fingerprints, toxicology tests, and hairs. The prosecution may also ask their own expert witness to testify to rebut the testimony of the defense side’s expert.
If mental competency is an issue in the case, a forensic psychiatrist can provide insight as to whether a defendant is competent enough to stand trial. In the event the insanity defense was used, a mental health expert witness can render an opinion regarding the defendant’s capacity and help the jury understand the issue.
Apart from clarifying scientific and technical matters, expert witnesses can evaluate the credibility of eyewitnesses and the authenticity of their testimony. They may also challenge the prosecution’s case by offering alternate interpretations of theories. In addition, some types of experts may be brought into a case to reconstruct the crime scene. No matter what type of witness is used, their role is to help your attorney introduce reasonable doubt and undermine the prosecution’s case.
What is the Role of an Expert Witness?
The role of an expert witness can be essential in many criminal cases. Not only may an expert witness testify about the facts of a case, but they may also render their opinion and testify regarding the conclusion they drew from the facts. However, the evidence they provide in the form of testimony is not conclusive. The jury must determine the weight the expert witness’s testimony should hold.
Specifically, an expert witness may do the following in a criminal case:
- Educate the jury about a specific issue
- Explain technical subjects to the court
- Challenge subjective interpretations of evidence
- Provide objective analysis and insight
- Help the jury weigh the evidence or trustworthiness of witness testimonies
- Issue written reports as required
Expert witnesses do not provide legal advice or advocate on behalf of either side. While your attorney will fight for your rights, an expert witness’s job is to give testimony that is neutral, objective, impartial, and unbiased — regardless of how it will affect the outcome of the case.
Contact an Experienced Oklahoma Criminal Defense Attorney
If you’ve been arrested or are being investigated for a criminal offense, it’s crucial to have reliable representation who knows how to fight for your rights and develop the best defense strategy possible. With offices in Tulsa and Claremore, Titus Hillis Reynolds Love provides skillful defense to clients who are facing criminal charges throughout Oklahoma and are dedicated to achieving a positive outcome in every case. Contact us online or call (918) 216-0892 to schedule a consultation.
