Evidence law: Types of evidence - Exculpatory + Inculpatory + Demonstrative + Lies

Exculpatory evidence is evidence favorable to the defendant in a criminal trial that exonerates or tends to exonerate the defendant of guilt. It is the opposite of inculpatory evidence, which tends to present guilt.

In many countries, including the United States, police and prosecutors are required to disclose to the defendant exculpatory evidence they possess before the defendant enters a plea (guilty or not guilty).

Per the Brady v Maryland decision, prosecutors have a duty to disclose exculpatory evidence even if not requested to do so. While the prosecution is not required to search for exculpatory evidence and must disclose only the evidence in its possession, custody, or control, the prosecution's duty is to disclose all information known to any member of its team, for example, police, investigators, crime labs, et cetera. In Brady v Maryland, the U.S. Supreme Court held that such a requirement follows from constitutional due process and is consistent with the prosecutor's duty to seek justice.

Inculpatory evidence is evidence that shows, or tends to show, a person's involvement in an act, or evidence that can establish guilt. In criminal law, the prosecution has a duty to provide all evidence to the defense, whether it favors the prosecution's case or the defendant's case. Evidence that tends to show a person's innocence is considered exculpatory evidence.

For example, if a man is poisoned to death by an overdose of arsenic, and a bottle of arsenic is found in the purse of his wife, that bottle could be considered inculpatory evidence against his wife. The bottle of arsenic in his wife's purse could also be considered exculpatory evidence, tending to show the man's innocence as far as suicide is concerned.

Demonstrative evidence is evidence in the form of a representation of an object. This is, as opposed to, real evidence, testimony, or other forms of evidence used at trial.

A lie is a statement used intentionally for the purpose of deception. The practice of communicating a lie is called lying; a person who communicates a lie may be termed a liar. Lies may be employed to serve a variety of instrumental, interpersonal, or psychological functions for the individuals who use them. Generally, the term "lie" carries a negative connotation and, depending on the context, a person who communicates a lie may be subject to social, legal, religious, or criminal sanctions.