In the law of the United States, a deposition is the out-of-court oral testimony of a witness that is reduced to writing for later use in court or for discovery purposes. It is commonly used in litigation in the United States and Canada and is almost always conducted outside of court by the lawyers themselves (that is, the judge is not present to supervise the examination). In other countries, testimony is usually preserved for future use by way of live testimony in the courtroom, or by way of written affidavit.
A minority of U.S. states, like New York, refer to the deposition as an "examination before trial" (EBT). Deposition is the preferred term in U.S. federal courts and in the majority of U.S. states, like California, because depositions are sometimes taken during trial in a number of unusual situations. For example, in some states, the litigation process may be drastically accelerated if the plaintiff is dying from a terminal illness.
Depositions are a part of the discovery process in which litigants gather information in preparation for trial. Some jurisdictions recognize an affidavit as a form of deposition, sometimes called a "deposition upon written questions." The routine practice of obtaining the oral evidence of a witness before trial is foreign to common law jurisdictions such as England, Australia and New Zealand. Having the right to pose oral questions to opposing parties in litigation before trial developed in Canada and the United States in the nineteenth century.