Depositions and Affidavits

When a party or witness offers sworn testimony in an affidavit or at deposition, the element of surprise may not be part of their trial testimony.

Seasoned trial lawyers have a saying that goes something like this: “Never ask a witness a question unless you already know the answer.” From a strategy standpoint, both sides of a civil lawsuit want to know what a witness will say before he or she takes the stand during trial. The goal is to avoid surprises -- especially the kind that can derail a case -- while making sure that the witness does not change the story he or she told leading up to the trial. The best strategy here is to have the witness give a pretrial statement under oath. That means getting the witness to declare their story in writing (in the form of an affidavit or declaration) or in deposition testimony. Let's take a closer look at these two litigation tools.

Affidavits and Declarations

An “affidavit” or “declaration” is a written out-of-court statement, signed and sworn to by the witness. In some jurisdictions an affidavit or declaration must involve a notary public or other official authorized who administers an oath and signs the document along with the declarant.

The affidavit or declaration must identify the person making the statement, the date on which it was made, and the location. The “statement” being sworn to in an affidavit or declaration is usually a series of affirmations (listed as numbered paragraphs) that methodically provide the witness’s observations or impressions of a certain event or issue, as well as the basis for those observations/impressions. In order to be admissible in court, most witness statements must be made on personal, first-hand information. However, a witness who has expertise in some technical or scientific field of work or study may prepare an affidavit or declaration that includes an opinion on an issue that falls within their expertise. This kind of “expert” affidavit or declaration will also include statements that show how and why the witness is professionally qualified to render an opinion.


In a deposition, one of the parties to a lawsuit or an important witness is asked a series of questions under oath, and the exchange is taken down by a court reporter. The entire deposition is then transcribed so that both sides can retain and review a copy.

When might a deposition be taken?

  • As part of the pretrial discovery process, both sides use depositions to gather facts about the case, and to get an idea of how a party or witness will testify in court -- not only what they might say, but also what kind of impression they might make on a judge or jury. Learn more about How Discovery Works in a Lawsuit.
  • If a witness is in poor health or lives far from where the trial is set to take place, an attorney may want to preserve that person’s testimony via a deposition.

In either situation, the attorney calling the deposition must give proper notice of the time, date and location. If a witness will not voluntarily appear for a deposition, the court may allow the parties to subpoena the witness and compel him or her to attend. (More on Subpoenas.)

During the deposition, the attorneys for either side may make objections to the relevance or form of a question, to get the objection on the record. Later on, the court can review and rule on those objections before trial. The deponent will usually be given an opportunity to review and make corrections to the deposition transcript as well.

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