The chief values of obtaining a deposition, as with any discovery proceeding, is to give all litigant parties in a contested case a fair preview of the evidence, and to provide support documents for further trials and dispositive motions. The process provides a "level playing field" of information among the litigants and avoids surprises at trial (traditionally regarded as an unfair tactic). Another benefit of taking depositions is to preserve a witness's recollection while it is still fresh, since the trial may still be months or years away. When a witness's testimony in open court is inconsistent with that given at deposition, a party can introduce the deposition to impeach (or contradict) the witness. In the event a witness is unavailable for trial (usually because they are deceased, seriously ill, or live hundreds of miles away), their deposition may be read or played before the jury and made part of the record in the case, with the same legal force as live testimony. In some states, stenographic, audio, or video records of depositions can be offered into evidence even if the witness is available. Deposition of the opposite party is often used to produce self-incriminating statements from the deponent, also document identification questions can make exhibits admissible for hearings and summary judgment motions.