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Expert Witness: How to Make or Break Your Case

Using an Expert Witness at Trial can Help or Hurt Your Cause

What exactly is an expert witness?  An expert witness is called to provide scientific, technical, or special knowledge. They will help jurors understand the evidence or determine the facts of the case.  The testimony of an expert witness is based on sufficient facts or data.  The testimony of the expert can also be based on specific methods and reliable principles that the expert can apply to the facts of the case. There are specific rules governing when experts can be used and for what. For more on that, see here.

Expert Witness; Trial Experts Can Make Your Case For You; Nicol Gersch Petterson Blog; Brain Circuitry Picture

Expert Witness-In General

To be considered an expert, specialized knowledge is needed. A person is considered qualified to be an expert based on their knowledge, skill, experience, training or education.  In order for the expert’s testimony to be considered, it is important that an expert witness establish their credibility as reliable through their work on previous cases, any publications they have sourced and also contributed to themselves, as well as their knowledge of the case and how their expertise can be applied to the facts of the case.

Expert Witness Qualifications

Before an expert can be used at trial–and even if the general public would think of them as an expert–they still have to jump through the procedural hoops to be “qualified” in a court of law.  Not every MD, for example, would be able to testify about coronavirus. For the court to allow their testimony, that doctor would have to prove that they’re recognized in their field as an expert on that subject, and sufficiently so that a jury would be able to rely on their testimony.  The governing law in Colorado is the Daubert standard (yes, that’s a case name), and it requires the party wishing to use the expert to prove the following things:

Under the Daubert standard, the factors that may be considered in determining whether the methodology is valid are: (1) whether the theory or technique in question can be and has been tested; (2) whether it has been subjected to peer review and publication; (3) its known or potential error rate; (4)the existence and maintenance of standards controlling its operation; and (5) whether it has attracted widespread acceptance within a relevant scientific community.

Criminal Expert Witness

Criminal trials often involve a number of different types of expert evidence. Depending on the type of case, you may be dealing with fingerprints, gun residue, relationships amongst parties, or even DNA.  Read below for more on each type of case and some of the common things we encounter in criminal trials.

Domestic Violence

In a domestic violence case, it is common for the prosecution to use an expert to assist their case.  Usually, the People’s expert is what we call a “blind witness” or someone who has not reviewed any evidence but will take the stand and testify about what they “expect” to see in these kinds of relationships.  See previous posts about DV power and control dynamics (including the cycle of violence) here and male victims of DV here. For more general information about DV, check out this link. When the People present an expert, it is important for the defense to–at the very least–consult with their own expert, especially in cases involving self-defense. Often, what works for us is to have our client actually interviewed by our defense expert, and have them review the evidence and materials and see if they agree with the People’s anticipated expert testimony. In this way, we can often frame this as an issue involving a “battle of the experts” and discount the testimony from the prosecution.

Sexual Assault and Strangulation

In a sexual assault case and in other felony assault cases like strangulation, SANE nurses (Sexual Assault Nurse Examiner) are used by the prosecution. Therefore, the defense should use a different SANE nurse to “battle” with the prosecution’s expert. These nurses and doctors have spent hours learning more about sexual assault the physical impacts of any intimate violence, they are the most helpful in these types of cases. They have also passed a board-certified exam that qualifies them as experts in sexual assault, making them an ideal expert witness–especially if you can use them in the defense’s case. For more about, SANE nurses and exams, check out this material.

DNA / Fingerprint / Forensic Expert

The use of DNA, fingerprints and other forensic evidence is also used in court, but not like you see on television. For more on this type of evidence (less about experts), come back next week to Nicol Gersch Petterson’s Blog.

Have questions about an expert witness or still need help?

Justie and Jenn at Nicol Gersch Petterson, P.C. are happy to help you understand the more expert or technical aspects of your case, including what an expert might cost to help you defend yourself. Please call or schedule a time to chat with our attorneys by using this link: https://Nicol Gersch PettersonScheduling.as.me/.