An affidavit is a sworn statement of fact that can be used in a variety of legal proceedings, from bankruptcy cases to family and civil litigation matters. A jury verdict that a criminal defendant is not guilty, or the finding of a judge that the evidence is insufficient to support a conviction.A written statement that someone makes after promising officially to tell the truth. An affidavit can be used as proof in a law court. After the Affidavit of Service is done, it must be filed with the Court. Com online Real Life Dictionary of the Law. Bouvier Law Dictionary. A written statement of fact that is sworn or affirmed to be true before a Commissioner for Oaths, Justice of the Peace or Notary Public. Step 2 — Fill out Forms. The courts are not to fill in the gaps in legislation.