Witness is a person who gives testimony in a judicial, legislative, or administrative proceeding. Such testimony is given under oath, or, if the witness’s religion forbids an oath, under affirmation. A witness may also be a person who signs a legal instrument, such as a will or deed, that another person executes in the presence of the witness.
A court witness is ordered to appear in court by a subpoena, which compels the person to attend and to give evidence. A person who fails to appear is liable to punishment for contempt of court. A witness who testifies untruthfully is guilty of the crime of perjury, and can be severely punished. Witnesses may legally refuse to testify against themselves or their spouses.
The question of who is suitable to serve as a witness is regulated by rules of evidence. The law considers certain people as unsuitable to give legal testimony. People who are insane and people who are too young to understand the nature of a binding oath are included in this class.