1 A person who observes the signing of a legal document in case it is subsequently necessary to verify the authenticity of the signature. He adds his own signature to the document as a witness. Many legal documents are only valid if properly witnessed (see deed; will).
2 In court proceedings, a person who gives evidence, either by way of a written statement or orally. In court, witnesses are required either to give evidence on oath or to affirm that their evidence is true. Most people are qualified to give evidence in any case (see competence) but there are certain exceptions; for example, when the judge considers the witness mentally unfit to give evidence. In civil cases a child who is too young to understand the nature of an oath is not a competent witness, although in criminal cases a young child may be allowed to give unsworn evidence. There is no minimum age below which a child cannot give evidence, but the judge has a discretion to determine whether or not a child is too young to be a competent witness. Most competent witnesses can be compelled to give evidence (a witness who refuses to answer is in contempt of court) but again there are exceptions. For example, a witness cannot be compelled to answer a question that may incriminate him. See also adverse witness; compellable witness; hostile witness.