What is an affidavit?

An affidavit is a written statement of facts sworn to be true before an authorized official.

Where the word "Affidavit" comes from

Affidavit comes from the Latin affidare, to pledge faith. It is a sworn written declaration, and courts have accepted affidavits for centuries as a way to put testimony in writing and hold the declarant accountable for its truth.

Why Affidavit matters

It lets courts and agencies receive evidence without live testimony in many situations, such as summary judgment motions, where affidavits set out the facts. Because it is made under oath, a false affidavit can support a perjury prosecution.

Common confusion about Affidavit

An affidavit is not the same as an unsworn statement or a mere letter. It must be signed under oath before a notary or other authorized person, and the notary's acknowledgment is what makes it an affidavit rather than a simple declaration, so the formalities matter.

A real-world example of Affidavit

In a summary judgment motion, the defendant files an affidavit from its warehouse manager stating that the product was shipped on time, and the court considers the sworn statement as evidence in deciding the motion.

A worked example of Affidavit

A plaintiff opposing a motion for summary judgment files an affidavit describing the accident and attaching a photo, swearing to the facts before a notary. The court considers the affidavit, but if it contains only conclusions or contradicts the plaintiff's own deposition, the court may disregard it. Because the affidavit is sworn, the plaintiff risks sanctions or perjury charges if it is false, which is why the formality gives the statement its evidentiary weight.

How Affidavit works in practice

When preparing an affidavit, state only facts you personally know, avoid conclusions and hearsay, and describe the basis of your knowledge, because courts disregard unsupported assertions. Sign it before a notary and keep the original. When attacking an affidavit, point out factual gaps or contradictions, because a conclusory affidavit will not carry the day at summary judgment.

DefineLaw editors — plain-English definitions for general reference; not a substitute for advice from a licensed attorney.