Legal confession

In legal psychology, a confession is a form of legal testimony, a statement by a suspect in crime which is adverse to that person. Some secondary authorities, such as Black's Law Dictionary, define a confession in more narrow terms, e.g. as "a statement admitting or acknowledging all facts necessary for conviction of a crime," which would be distinct from a mere admission of certain facts that, if true, would still not, by themselves, satisfy all the elements of the offense.

History
This specific form of testimony, involving oneself, is used as a form of proof in judicial matters, since at least the Inquisition. The value of confessions, however, are discussed, and law generally request cross-checking them with objective facts and others forms of evidence (exhibits, testimonies from witnesses, etc.) in order to evaluate their truth value. Confessions were first developed in the Roman Catholic Church under the Sacrament of Penance, where the confession of a sin is considered to be enough to absolve oneself. This aspect concerning moral guilt has been carried on in various legislative codes, in which a criminal is considered worse if he does not confess to his crimes.

Reliability
On one hand, confessions obtained under torture have often been considered as not objective enough, since the use of such means may lead to the suspect in confessing anything. However, when the confession reveal secret only known to the perpetrator (such as the location of the body or murder weapon), the confession is reliable.

On the other hand, even without torture, various cases of avered false confessions demonstrate that, in itself, one man's confession is not a sufficient proof. False memory (including memory biases, etc.) or privileges granted under plea bargaining might lead to such false confessions.

In Japan, the legal requirements dictate that confession is only admissible as evidence only if it contains elements only the guilty could have known. However, many miscarriage of justice cases in Japan are due to the police faking the confession of guilty secrets.

England and Wales
In English law a confession includes: "any statement wholly or partly adverse to the person who made it, whether made to a person in authority or not and whether made in words or otherwise."

A confession may be admitted in evidence so long as it is relevant to any matter in issue and not excluded under the court's discretion.

Exclusion of prosecution evidence
The court must exclude evidence:
 * if the "admission of the evidence would have such an adverse effect on the fairness of the proceedings that the court ought not to admit it", or
 * if it was obtained by torture.

The court may exclude evidence:
 * in its common law discretion if the prejudicial effect of the evidence outweighs the probative value, or
 * under section 76 of the Police and Criminal Evidence Act 1984.

Under section 76, following a representation by the defendant or upon the court's own motion, evidence tendered by the prosecution must not be admitted if it was or may have been obtained:
 * by oppression of the person who made it; or
 * in consequence of anything said or done which was likely, in the circumstances existing at the time, to render unreliable any confession which might be made by he accused in consequence thereof.

Whether or not evidence was obtained in such circumstances will be decided by a judge sitting without a jury in a voir dire.

Oppression includes torture, inhumane and degrading treatment and the use or threat of violence. Oppression imports "some impropriety... actively applied in an inappropriate manner by the police"

Under the second limb, a judge is not to consider whether the confession made was truthful, but rather whether, under the circumstances, "whatever was said or done, was, in the circumstances existing as at the time of the confession, likely to have rendered such a confession unreliable, whether or not it may be seen subsequently - with hindsight and in the light of all the material available at trial - that it did or did not actually do so". The question of whether some action has rendered a question unreliable centers on whether it is likely to have made an innocent person confess, or even (equivalently) to have made a guilty person confess to more than their actual crime.

"Anything said or done" is not limited to the actions of the police, but does not include things said or done by the accused. However, the circumstances existing at the time do include the accused's own mental state and capacities.

Evidence tendered by a co-defendant
The court may exclude evidence under section 76A of the Police and Criminal Evidence Act 1984. Following a representation by the defendant or upon the court's own motion, evidence tendered by a co-defendant of a defendant's confession must not be admitted unless the co-defendant proves on the balance of probabilities that it was not obtained:
 * by oppression of the person who made it; or
 * in consequence of anything said or done which was likely, in the circumstances existing at the time, to render unreliable any confession which might be made by he accused in consequence thereof.

Statements made in the presence of the accused
The common law rules on the admission of confessions are preserved, and apply so long as the statement was made voluntarily. Under the common law, where a statement is made in the presence of the accused, by a person with whom the accused is on even terms, upon an occasion which should be expected reasonably to call for some explanation or denial from him, the accused's acceptance of that statement , including by giving an insufficient explanation or by acquiescence. In deciding whether to put the matter to the jury, the judge should ask: (1) could a jury properly directed conclude that the defendant adopted the statement in question?

If so, (2) is that matter of sufficient relevance to justify its introduction in evidence?

If so, (3) would the admission of the evidence have such an adverse effect on the fairness of the proceedings that the judge ought not to admit it?

United States
In the 1936 case Brown v. Mississippi, the United States Supreme Court ruled that convictions which are based solely upon confessions coerced by violence violate the Due Process Clause.

Italy
Confessions have been used extensively in Italy since the creation of the pentito status. Adriano Sofri, for example, has been given a life-sentence exclusively on the words of one pentito.