Witness

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 legal proceedings.

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, or by a government agency.

In many jurisdictions, it is compulsory to comply with the subpoena and either take an oath or solemnly affirm to testify truthfully under penalty of perjury.

A percipient witness (or eyewitness) is one with knowledge obtained through their own senses (e.g., visual perception, hearing, smell, touch).

[1] A crown witness is one who incriminates former accomplices in a crime who following receive either a lower sentence, immunity or also a protection of themselves or/and their family by the court.

[4] Mistaken eyewitness identification may result from such factors as faulty observation and recollection, or bias, or may involve a witness's knowingly giving false testimony.

If several people witness a crime, it is possible to look for commonalities in their testimony, which are more likely to represent events as they occurred, although differences are to be expected and don't of themselves indicate dishonesty.

Witness identification will help investigators get an idea of what a criminal suspect looks like, but eyewitness recollection include mistaken or misleading elements.

[8] The formal study of eyewitness memory is usually undertaken within the broader category of cognitive processes, the different ways in which we make sense of the world around us.

That is done by employing the mental skills at one's disposal like thinking, perception, memory, awareness, reasoning, and judgment.

If one were to accept that the way people think, perceive, reason, and judge is not always perfect, it becomes easier to understand why cognitive processes and the factors influencing the processes are studied by psychologists in matters of law, one being the grave implications that this imperfection can have within the criminal justice system.

As Huff and Rattner[9] note, the single most important factor contributing to wrongful conviction is eyewitness misidentification.

For example, in most common law jurisdictions, at least two witnesses must sign their names to a will in order to verify that it was executed by the testator.