A written statement that someone makes after promising officially to tell the truth. An affidavit can be used as proof in a law court.Word History and Origins​​ Origin of affidavit1. An affidavit is a written statement that you swear is true and that may be used as evidence in a court of law. Before me, the undersigned authority, a notary public, personally appeared. Both copies will be required in court. If an affidavit is filed, the. Sheriff's poundage will be calculated based on the consideration set forth in the affidavit. Petition for Probate of Authenticated Copy of Will(PDF, 6MB) - Complete this form and present it when filing authenticated record.