Legal System

The Role of Witnesses


Witnesses play a very important role in criminal cases. They help to clarify what happened by telling the judge or jury everything they know about an event.

A witness is someone who has relevant information about a crime. Both the lawyer for the government and the accused can require witnesses to come to court to tell this information to the judge, and sometimes to a jury.

Witnesses must make an oath or solemnly state that they will tell the truth in court. In special cases, witnesses who are under the age of 14 or have an intellectual disability can simply promise to tell the truth.

Types of Witnesses

There are two types of witnesses in a criminal case: ordinary witnesses and expert witnesses.

Ordinary Witness

Expert Witness

Who is this witness?

An ordinary witness is someone who personally saw or heard something about the crime.

An ordinary witness can be the police officer who made the arrest or a person who was at the scene of the crime.

An expert witness is someone who has special expertise about an element of the crime.

An expert witness can be a doctor, psychologist, accountant, etc.

What can the witness talk about?

Ordinary witnesses must answer the lawyers’ questions and tell the judge what they saw or heard.

They do not give their opinions about what happened.

Expert witnesses interpret the facts of the case and give their opinions (e.g., an opinion on the mental state of the accused when the crime was committed).

The information provided by witnesses becomes part of the evidence. The evidence determines whether the accused actually committed the crime. The judge or jury considers all the evidence, including what the witnesses said, when deciding whether the accused is guilty or innocent.