Witness: Definition & Role in Criminology

Instructor: Elisha Madison

Elisha is a writer, editor, and aspiring novelist. She has a Master's degree in Ancient Celtic History & Mythology and another Masters in Museum Studies.

A witness has an intrinsic role in a trial. This lesson with define the different types of witnesses, their roles, and the aspects that could damage their credibility.

What is a Witness?

During a trial either civil or criminal, one of the most important aspects are the witnesses. A witness helps define and enlighten information about an incident or crime, which allows the lawyers and jury to understand everything about a case. Think of them like a translator in a foreign country. They help explain the aspects of a crime from new points of view.

Witnesses can be anyone that witnessed the crime to the actual victims of the crime itself. For example, if there was a murder, an eye-witness can explain what they saw, allowing for a better understanding of the crime and who committed it. If there had been no eye-witness, there is a possibility the criminal would go free.

Witnesses can be pulled from both the defense lawyers or the prosecution. The goal from both sides of calling witnesses is to make sure everything is known about a person or event. However, witnesses are also assessed by their credibility. Things that could make a less credible witness are:

  • Bias about the defendant or accuser
  • Alcoholic or drug abuser
  • No job, homeless
  • Criminal past


Witness Stand
Witness Stand

Now that we have learned the role of a witness, it is important to learn about the different types of witnesses.

  • Expert witness - Someone who has an education on a specific subject that has been called to testify. For example, a psychologist that has been called to testify on the mental state of the accused. Other experts could be forensic scientists, arson investigators, and auto mechanics. Anyone that has the expert ability to testify on a subject is an expert witness.

  • Eye-witness - People that saw the crime take place, heard about the crime taking place, or were involved with seeing or hearing aspects that pertain to the crime. Say you are a hair dresser and overheard someone talk about how they drove the getaway car in a robbery. You may not have seen the actual crime, but you did see and hear about the crime, so you might be called in as a witness.

  • Character witness - Used to prove personality and behavioral traits about someone. For example, as a student of a professor who is now accused of rape, the defense could call you in to testify about the congenial nature of the professor and how he was always respectful of you and your space.

Role in the Criminology Process

Witnesses will usually have several roles as they go through the process of testifying. There will be interviews and depositions with the witnesses to determine what they know and how they will clearly describe the events in court. The interviews can be done by both the defense and prosecution, which can be stressful for witnesses.

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