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Role of Expert Witnesses in Loudoun County DUI Drug Cases

With DUI drug cases, it is important for Loudoun County DUI drug defense attorneys to know their opposition. In this case, it is important to know what evidence is likely to be presented by the prosecution in a DUI case. Under Virginia Rules, the Commonwealth’s Attorney is generally not required to give notice on their intent to introduce potential evidence. However, they are typically required to give notice on their intent to introduce evidence by an expert witness.

The most common type of expert witness that will be offered by the prosecution in a DUI or DUID case is a toxicologist. Typically, this person is an employee of the Virginia Department of Forensic Science (DFS). This is the DFS toxicologist who will examine the blood of the accused, do certain testing on them and be prepared to testify about the contents of the blood and how that would potentially impair a person under those circumstances. When your case is going to involve prosecution expert witness, you and your DUI defense attorney should be armed with your own expert witness to assist in the defense of your case.

How Does A Loudoun DUI Lawyer Refute Or Challenge The Claims Of The Government’s Experts? Do You Use Different Experts Or?

There are multiple ways to refute or impeach the prosecution’s expert witnesses in a DUID case. The most common methods are:

  • Cross-examination
  • Presentation of contrary expert witness testimony by means of a defense expert

In cross-examination, it is possible to get an expert witness to back off from some of the strong assertions that they have made and have the case reduced. In addition, in any criminal case the defense has the ability to offer their own expert witness testimony. This is often done through defense expert toxicologist to review the facts of the case, review the medical records, prepare them to testify about how those medical records and how that person’s behavior may or may not be consistent with the opinions of the prosecution’s expert.

So Why Is It Important To Have An Attorney Who Knows Good Experts?

If you have an attorney who is inexperienced about expert witness testimony, they may be unable to lay proper evidentiary foundation to allow your expert to testify to the full extent of their knowledge. In addition, an attorney who is unfamiliar with DUID cases maybe unable to tactically cross-examine the prosecution’s expert. Their expert may look stronger than your expert, and your case will look weaker as a result. In addition, if you have an attorney who does not have knowledge of relevant experts in the field applicable to your case, you may be unable to locate a strong expert witness to come in on your behalf

How Are Expect Witnesses Used At Trial?

An expert witness will be used in the following manner in a trial. After the presentation of direct evidence testimony, there will be a certain foundational evidence that will be made by either the prosecution or the defense depending on whose expert is about to testify. The expert will take the stand, introduce themselves, explain the relevant experience and attempt to get qualified by the court.

Expert qualification means that the court accepts that the person is an expert in the field and will ask them to give opinion evidence. A lay person such as a police officer or other witness is not qualified to give opinion testimony and such testimony is likewise excluded by the fact finder.

After the expert witness is qualified, they will testify as to what they based their opinion on. Typically in a DUID case, it will include examination of all relevant case information, as well as what tests and procedures they performed.

For example, a prosecution toxicologist testifies as to their knowledge and background as a toxicologist, their training, what tests they performed on the blood sample and the test results of the blood sample.

Northern Virginia Criminal Defense Group

Northern Virginia Criminal Defense Group
Northern Virginia Criminal Defense Group
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Leesburg VA 20175
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Warrenton VA 20186
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Manassas VA 20110
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