Defense attorneys often rely on expert witnesses in making their case to the jury. In actuality, these can be a broad category of people who can provide different types of assistance to the defense’s case. Given that the prosecutor must prove their case beyond a reasonable doubt, an expert witness could help cast doubt on the case being made against you.

The type of expert witness that you may use depends on the case against you. Most of us think that an expert witness will take the stand to give their opinion on the evidence against you. As you will see below, that is typically the case, but not always so.

Experts Can Help With Strategy

Your defense attorney may need some extra assistance to learn what angles to pursue when they are both putting on your case and cross-examining the witnesses that are being used against you. Consulting experts can be every bit as important as the ones who testify against you. They can help your attorney figure out the strategy that will be used in your defense, especially if your case goes to trial. These experts are especially helpful when you are dealing with a complex set of facts. Consulting experts are even more critical when prosecutors may need to follow a possible money trail to prove their case.

When you use consulting experts, they do not need to pass any tests of their credentials that the court imposes if they are not going to testify. The prosecutor does not necessarily even know that they are working on your case. They are simply using their expertise to advise your lawyer on ways that they can defend the case against you. However, your lawyer would make sure before they hire the expert that they really have the knowledge and ability to help your case.

Expert Witnesses Need Qualifications in Relevant Areas

If an expert is going to testify in court, it is a different story. Here, you are relying on their credentials and expertise to sow reasonable doubt about the prosecutor’s case. Therefore, they must have the relevant knowledge and expertise to testify. A testifying expert must have:

  • Training, skill, education, experience, or knowledge relevant to the opinion
  • Technical, scientific, or other specialized knowledge will help the jury in understanding a fact in issue or the evidence

There is a difference between expert testimony and that of a layperson. The latter is someone who is testifying about a fact. Usually, it is something that they saw directly. They do not need to have any particular expertise. Their only qualifications necessary are they were at the scene or knew one of the parties.

Judges will scrutinize the expert’s credentials in light of the testimony that they intend to give. Judges may not allow the expert to testify if they do not believe that they have relevant knowledge or credentials. If one is not allowed to testify as an expert, their opinion would not have much use as a lay witness, nor may it even be admissible. You can expect that the prosecutor will challenge the credentials of nearly every expert that you call to testify on your behalf.

Different Types of Experts Who Can Help Your Defense

The most common type of expert in a criminal case is one who will give their opinion on the physical evidence being used against you. For example, if the prosecutor is relying on DNA evidence to make their case, you can have a DNA expert of your own give their opinion on the strength of the evidence and potentially call it into question. Experts can also be used to weigh in on other types of physical evidence, including:

  • Blood spatters or stains
  • Fingerprints
  • Hairs
  • Firearms or weapons

There are other issues in your case that could benefit from an expert. For example, if law enforcement has seized evidence from a computer or laptop, an expert may give their opinion of the authenticity of the evidence and whether the device was really yours, and who else may have had access to it.

If you elect to fight DUI charges against you, an expert could be the key to your case. An expert can give their opinion of the following:

  • The toxicology tests
  • The chain of custody for the evidence being used against you
  • Forensic evidence specialists

Polygraph Experts Are Not Allowed

One type of expert that you cannot use in Wisconsin is one who will provide an opinion about a polygraph. This type of evidence, or any opinions relating to it, are not admissible in Wisconsin criminal cases.

An experienced attorney would review the evidence and case against you and consult with an expert well in advance of trial. Their opinion could even bear on whether you fight the charges or try to negotiate a plea agreement.

Your lawyer would have experts that they have regularly worked with and would know how to use them in your defense effectively. When the prosecutor must prove their case beyond a reasonable doubt, a persuasive expert could be the grain of salt that the jury needs to doubt what the prosecutor is saying. Expert witnesses can be a key part of an aggressive defense strategy to win your case. These witnesses may testify after the prosecution rests when it is time for your attorney to present your case to the jury.

Contact an Appleton Criminal Defense Lawyer

When you are facing criminal charges and the prospect of a difficult trial, an aggressive and experienced attorney is a must. At Hogan Eickhoff, we have gotten results for clients facing complex and tough cases. We work to understand both your case and your own particular circumstances before we get to work on your behalf. To schedule a free initial consultation, you can send us a message online or contact us at (920) 450-9800. It is very important to contact us as soon as you learn that you have been charged or are being investigated.