Literally, a "putting down."
The word has been used to refer to the removal of a person from a position of authority or power.
It can also be used to refer to the leaving of a deposit (as in a mineral deposit) or the deposit itself.
In law, a deposition is the act or fact of taking sworn testimony of a witness outside of court, in certain well-defined circumstances. It is a part of the discovery process whereby litigants obtain information from each other in preparation for trial. Some jurisdictions recognize an affidavit as a form of deposition.
In American judicial proceedings in most jurisdictions, however, certain conventions are almost always observed in the taking of a deposition. The person to be deposed , known as the deponent, is usually notified to appear at the appropriate time and place by means of a subpoena. A court reporter, also known as a stenographic reporter (sometimes denoted "CSR" for Certified Stenographic Reporter) is present and begins the proceedings by administering the same oath that the deponent would take if the testimony were being given in court. Thereafter, the court reporter makes a verbatim stenographic record of all that is said during the deposition, in the same manner that witness testimony is recorded in court. Many CSR's nowadays also make a contemporaneous audio recording.
Attorneys for at least two, and often all of the litigants involved in the action are present to represent the interests of their respective clients. The attorney who has ordered the deposition begins questioning of the deponent (this questioning is referred to as "direct examination" or "direct" for short). Since nods and gestures cannot be recorded, the witness is instructed to answer all questions aloud. After the direct examination, other attorneys present cross-examine the witness. The first attorney may ask more questions at the end, in re-direct, which may be followed by re-cross.
During the course of the deposition, one attorney or another may object to questions asked. The purpose of this is to preserve the objection for trial. Usually, the deponent will still be instructed to answer the question, but between the time of the deposition and the time of trial, a judge may be asked to rule on objections made during the deposition. Any objection which is upheld will result in the exclusion of evidence given in response to it from being presented at trial.
The chief value of a deposition, as with any discovery proceeding, is to give all litigant parties in a contested case a fair preview of the evidence so that a "level playing field" is achieved and surprise (traditionally regarded as an unfair tactic) is avoided at time of trial. Another benefit of deposition is to preserve a witness' recollection while it is still fresh, though the trial may still be some time off. In the event a witness dies or is otherwise unavailable for trial, his deposition testimony may be read into the record.
Some depositions are videotaped, in anticipation of the unavailability of a witness at trial, so that if necessary the videotape may be played for judge and jury.
Sometimes, after a number of witnesses have been deposed, the parties will have enough information that they can reasonably predict the outcome of a prospective trial, and may decide to arrive at a compromise settlement, thus avoiding trial and preventing additional costs of litigation.