Testimony refers to the oral evidence given by witnesses at trial. In criminal trials, evidence is brought forth mainly through the testimony of witnesses. Both the Crown and defence are permitted to call witnesses to advance their case. When a party questions their own witness, the questioning is known as “examination in chief”. Both parties also have the right to question the other party’s witness. This line of questioning is known as “cross-examination”.

The purpose of the cross-examination is to point out weaknesses in the opponent’s case and inconsistencies or inaccuracies in the witnesses’ testimony. During cross-examination, the party asking the questions can only ask questions about the evidence given by that witness during examination-in-chief.

The Crown and defence counsel have discretion to call whomever they wish as a witness, as long as the witness has relevant information regarding the alleged offence. The Crown and defence counsel also have the discretion not to call a particular witness.

While the Crown usually calls at least one witness to make their case, the defence is not required to call any witnesses. This is because the burden lies with the Crown to prove their case beyond a reasonable doubt. In rare cases, the Crown may make their case without a witness. The defence is not required to present a defence at all. If the Crown cannot meet their burden, the accused cannot be convicted.


Person A is on trial for assaulting person B. At trial, the Crown calls person B as a witness and ask questions regarding what occurred on the night of the alleged assault. This is the Crown’s examination in chief. Person B testifies during examination in chief that on the night in question, person A punched her in the face, causing a black eye.

When the Crown is done with their examination in chief of person B, it is the defences turn to cross-examine person B. Defence counsel asks person B specific questions regarding what they testified about during the examination in chief. Defence counsel questions person B about inconsistencies between the testimony she gave in her examination in chief, and the testimony she gave during cross-examination.

Testimony as Evidence at Trial

Testimony is the most common type of evidence. Almost all criminal trials have at least some testimony. In some cases, testimony is the only evidence available. An individual can be convicted of a criminal offence based on the testimony of another individual alone. In many cases there is no physical evidence for the Crown to present and so they must prove their case with the testimony of witnesses.


In many sexual assault cases, testimony is the only evidence available and the only evidence required to convict the accused. In these types of cases, the complainant will testify at trial that they were sexually assaulted by the accused. If the court finds their evidence to be consistent and accurate, and are convinced beyond a reasonable doubt, the accused will be convicted.

Trial Procedure

At trial, the Crown calls their witnesses first. They advance their case by questioning the complainant or witnesses regarding the alleged offence that forms the subject matter of the trial.

Once the Crown has completed their examination in chief of their first witness, the defence will have an opportunity to question (cross-examine) that witness about the evidence they just provided to the Crown, as well as any other statements they have made about the matter under oath (i.e. police statements). This pattern is repeated until the Crown has called all of their witnesses and rested their case.

Once the Crown is done calling witnesses, the defence is given an opportunity to call witnesses, including the accused, to testify. The defence is under no obligation to call any witnesses. If they do choose to call a witness, they will complete their examination in chief of that witness. Then, the Crown will be given an opportunity to cross-examine the witness. This pattern is repeated until the defence has called all of their witnesses.

Who can Testify?

The Crown and defence counsel both have the right to call as many witnesses at trial as necessary. A witness can be anyone with first-hand knowledge about the matter they are being questioned about. The information elicited from the witness must be relevant to the case at hand and must advance the case in some meaningful way.

The Complainant

In cases involving offences against a person, the victim, known as the complainant, will often testify. For example, in a sexual assault case, the victim of the sexual assault will often be the Crown’s main witness. The testimony of the complainant alone, if believed by the court, is enough to convict the accused.

The Accused

While the accused has the right to testify at their own trial, they cannot be compelled to do so. It is up to the accused and their counsel to determine whether testifying at trial is appropriate.

If the accused does choose to testify, the Crown will have an opportunity to cross-examine them.

If the accused made a statement to police when they were arrested, the Crown may use this statement against the accused if the accused testifies differently at trial. If the Crown is able to point out inconsistencies in the accused’s testimony, it could affect their credibility and reliability in providing evidence.

Friends and Family of the Accused

Friends and/or family of the accused may be called to testify at trial. Generally, a witness can be forced to testify at trial even if they do not want to. In extreme cases, the Crown can even have an uncooperative witness arrested on a “material witness warrant”, which allows the police to physically force the witness to attend court during the trial.

Spousal Privilege

When the accused is married, their spouse cannot be forced to testify against them. The spouse may testify if they wish, but they cannot be compelled to by the court. For spousal privilege to exist, the parties must be legally married at the time of the trial and must have been legally married at the time of the alleged incident they are being questioned about.


Person A is charged with murder. The Crown believes person A’s girlfriend, person B, was present at the time of the killing and subpoenas her as a witness at trial. At trial, person B claims spousal privilege because she and the accused got married the day prior. Spousal privilege does not exist because while the parties were married at the time of trial, they were not married at the time of the alleged killing. As a result, person B can testify regarding what she witnessed on the night of the alleged murder.

The Police

Police are often important witnesses in criminal trials. In some cases, police may be the only witness called by the Crown. As with any other witness, when the Crown calls a police officer as a witness, the defence will have the opportunity to cross-examine the officer once the Crown is done with their line of questioning.

Depending on the type of offence, police may testify at trial for a variety of reasons. In an impaired driving case, the arresting officer would likely be called to testify regarding what they witnessed in regard to the accused’s driving on the night of the alleged offence.

In a child pornography case, a detective who worked on the case may be called to testify about how law enforcement traced the child pornography material to the accused.

In a domestic assault case, the responding officer may be called to testify about what he witnessed when he arrived at the alleged crime scene.

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