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Competence and Compellability of Witnesses

Under the Evidence Act 1995, there is a presumption that everyone is competent to give sworn evidence in a legal proceeding and any competent person can be compelled to be a witness. However, this presumption can be rebutted by a party demonstrating that the person called as a witness lacks capacity. The act also sets up exceptions to the rule that everyone is a competent witness. This article outlines the rules surrounding the competence and compellability of witnesses. 

When does a person lack competence?

A person is not a competent witness if they do not have the capacity to understand or answer questions about the facts at issue in the proceeding and this incapacity cannot be overcome. This may be because of a disability because the person is a very young child or for some other reason.

Competence must not be confused with credibility. A witness with poor powers of observation or an imperfect memory does not lack competence. Competence refers to whether a person can function as a witness.

A person may be competent as a witness in relation to some matters but not others.

The issue of whether a person is a competent witness is for the magistrate or judge to decide on the balance of probabilities. If the matter is being decided by a jury, the judge must decide the issue of the competence of a witness in the jury’s absence.

Competence and Unsworn evidence

At common law, a person is only competent as a witness if they can give sworn evidence. This means they need to be able to understand the oath or affirmation. However, under Section 13 of the Evidence Act, a person who cannot give sworn evidence because they do not understand the oath or affirmation can still give unsworn evidence.

Before a witness can give unsworn evidence, they must:

  • Be told that it is important to tell the truth;
  • Be told that they may be asked questions they do not know the answer to and that they should tell the court if this occurs;
  • Be told not to feel pressured to agree with statements that are not true.

When is a person not compellable?

There are a number of situations set out in the Evidence Act where a person is not compellable as a witness.

Reduced capacity

Under Section 14, a person is not a compellable witness if the court considers that there would be a substantial cost or delay involved in ensuring that they understand and can answer questions and there has already been adequate evidence given on the matter by others.


A defendant is not a compellable witness against a co-defendant.

Family members

A spouse, de facto partner, parent or child of the accused may object to being required to give evidence for the prosecution. A person who makes such an objection must not be required to give the evidence if the court finds:

  • there is a likelihood doing so would harm the person or their relationship with the accused; and
  • that harm outweighs the desirability of the evidence being given.

In determining this, the court must consider the offence for which the accused is being tried, the nature of the evidence the witness is expected to give and whether any other evidence is available. The court must also consider the relationship between the person and the accused and whether giving evidence would necessarily involve them to disclose matters told to them in confidence.

State officials

 The following persons are not compellable to give evidence under section 15 of the act:

  • The sovereign;
  • The governor-general;
  • The Administrator of a Territory;
  • The Governor of a state;
  • The head of state of another country.

Members of parliament are also not compellable witnesses where attending to give evidence would prevent them from attending parliament or a meeting of a parliamentary committee.

Compelling a person to give evidence

When a party requires a person to attend to give evidence in a proceeding, it issues a subpoena for the person to attend court. A person who has received a subpoena must attend court on the specified date and if they fail to do so, the court may issue a warrant for their arrest. If a person who is subpoenaed to give evidence believes they are not compellable as a witness, they must attend court and inform the court of this.

If a person is compellable, they must answer all the lawful questions that are put to them. A person who refuses to answer a lawful question may be charged with contempt of court.

If you require legal advice or representation in a criminal law matter or in any other legal matter please contact Armstrong Legal.

Fernanda Dahlstrom

This article was written by Fernanda Dahlstrom

Fernanda Dahlstrom has a Bachelor of Laws, a Bachelor of Arts and a Graduate Diploma in Legal Practice. She has also completed a Master’s in Writing and Literature. Fernanda practised law for eight years, working in criminal defence, child protection and domestic violence law in the Northern Territory and in family law in Queensland.

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