An alibi is a form of defense used in criminal procedure wherein the accused attempts to prove that they were in some other place at the time the alleged offense was committed. The Criminal Law Deskbook of Criminal Procedure states: "Alibi is different from all of the other defenses; it is based upon the premise that the defendant is truly innocent." In Latin, alib? means "somewhere else."
In some legal jurisdictions there may be a requirement that the accused disclose an alibi defence prior to the trial. This is an exception to the rule that a criminal defendant cannot normally be compelled to furnish information to the prosecution. Since the alibi involves evidence of innocence rather than guilt, the privilege against self-incrimination is not implicated.
In Canada, the defence must disclose an alibi defence with sufficient time for the authorities to investigate the alibi, and with sufficient particularization to allow for a meaningful investigation. Failure to comply with the two requirements will result in the court making an adverse inference against the alibi defence (but will not result in the exclusion of the alibi defence).
Conversely, some judges in other jurisdictions have held the opinion that the mandatory early disclosure of alibis is unfair, possibly even unconstitutional.
The giving of a false alibi, beside resulting in possible subsequent criminal offences (obstruction of justice, perjury, etc.), may, in some jurisdictions, result in negative ramifications for the trial itself.
An alibi agency, also called an alibi network, forges explanations for unexcused absences, e.g. due to an extramarital affair or adultery. In other words, alibi agencies are paid to lie for their customers. Originating in 1990s Japan, such services appeared in Europe in 2004, where they were condemned as immoral by the Catholic Church in Germany. They are the subject of the 2006 movie The Alibi.