A witness is someone who has, who claims to have, or is thought, by someone with authority to compel testimony, to have knowledge relevant to an event or other matter of interest. In law a witness is someone who, either voluntarily or under compulsion, provides testimonial evidence, either oral or written, of what he or she knows or claims to know about the matter before some official authorized to take such testimony.

A percipient witness or eyewitness is one who testifies what they perceived through his or her senses (e.g. seeing, hearing, smelling, touching). That perception might be either with the unaided human sense or with the aid of an instrument, e.g., microscope or stethoscope, or by other scientific means, e.g.,a chemical reagent which changes color in the presence of a particular substance.

A hearsay witness is one who testifies what someone else said or wrote. In most court proceedings there are many limitations on when hearsay evidence is admissible. Such limitations do not apply to grand jury investigations, many administrative proceedings, and may not apply to declarations used in support of an arrest or search warrant. Also some types of statements are not deemed to be hearsay and are not subject to such limitations.

An expert witness is one who allegedly has specialized knowledge relevant to the matter of interest, which knowledge purportedly helps to either make sense of other evidence, including other testimony, documentary evidence or physical evidence (e.g., a fingerprint). An expert witness may or may not also be a percipient witness, as in a doctor or may or may not have treated the victim of an accident or crime.

A reputation witness is one who testifies about the reputation of a person or business entity, when reputation is material to the dispute at issue.

In law a witness might be compelled to provide testimony in court, before a grand jury, before an administrative tribunal, before a deposition officer, or in a variety of other proceedings (e.g., judgment debtor examination). Sometimes the testimony is provided in public or in a confidential setting (e.g., grand jury or closed court proceeding).

Although informally a witness includes whoever perceived the event, in law, a witness is different from an informant. A confidential informant is someone who claimed to have witnessed an event or have hearsay information, but whose identity is being withheld from at least one party (typically the criminal defendant). The information from the confidential informant may have been used by a police officer or other official acting as a hearsay witness to obtain a search warrant.

A subpoena commands a person to appear. It is used to compel the testimony of a witness in a trial. Usually, it can be issued by a judge or by the lawyer representing the plaintiff or the defendant in a civil trial or by the prosecutor or the defense attorney in a criminal proceeding. In many jurisdictions, it is compulsory to comply, to take an oath, and to tell the truth, under penalty of perjury.

Read more about Witness:  Reliability, Credibility of A Witness

Other articles related to "witness":

List Of The Bill Characters (M-P) - M - Neil Manson
... learns that the NCS are investigating whether Neil is influencing a witness in a major money-laundering trial who is a client of his wife, Philippa ... This woman is a key witness in a case, and the NCS team have evidence of Neil meeting with her ... Neil tells Jack that he met with the witness because the witness was afraid for her life ...
List Of Due South Episodes - Season 4: 1998–99
13 September 1999 Fraser and Kowalski protect a witness before he testifies ... However, after losing said witness, its up to Fraser to go undercover...in a coffin! 323 ... "Say Amen" George Bloomfield John Krizanc 4 March 1999 (1999-03-04) 20 ...
Special Tribunal For Lebanon - Controversies - False Witnesses
... The tribunal has stated, however, that he is no longer considered a credible witness ... Al Sadiq should be tried for acting as a false witness ... He also said Siddiq was never questioned by the judicial authorities, but only as a witness by the International Committee after leaving Lebanon in April 2005 ...
List Of Last Survivors Of Historical Events - 1915–1930
... Smout June 22, 2004(2004-06-22) (aged 106) Last witness to the death of the Red Baron and veteran of the Battle of Messines June 7 to 14, 1917, and April 21, 1918 Albert Dacosta Riches October 1, 2000(2000-10-0 ... June 29, 2009(2009-06-29) (aged 113) Last witness of the Amritsar Massacre April 13, 1919 Veysel Turan March 25, 2007(2007-03-25) (aged 106) Last veteran of the ...
Credibility of A Witness
... Generally, a witness is deemed to be credible if they are recognized (or can be recognized) as a source of reliable information about someone, an event, or a phenomenon ...

Famous quotes containing the word witness:

    Since body and soul are radically different from one another and belong to different worlds, the destruction of the body cannot mean the destruction of the soul, any more than a musical composition can be destroyed when the instrument is destroyed.
    —Oscar Cullman. Immortality of the Soul or Resurrection of the Dead? The Witness of the New Testament, ch. 1, Epworth Press (1958)

    That he is old, the more the pity, his white hairs do witness it.
    William Shakespeare (1564–1616)

    Against my will, I became a witness to the most terrible defeat of reason and to the most savage triumph of brutality ever chronicled ... never before did a generation suffer such a moral setback after it had attained such intellectual heights.
    Stefan Zweig (18811942)