Lawsuits involve applying law to fact; at the heart of any lawsuit, therefore, is a mantra from "Dragnet's" Joe Friday: "Just the facts, ma'am." Litigants have multiple ways to present facts; two common forms are witness testimony and affidavits. An affidavit is a written document, signed under oath or affirmation. Because the affidavit is a sworn document, the affiant (the person who gave the statement) is guilty of perjury if he lies in the document. Affirm an affidavit by signing it under oath.
Draft the affidavit. In the affidavit, include the facts and circumstances pertinent to the case. Facts generally include the name and birth date of the affiant and a description of what the affiant saw or witnessed.
Take the document to court or to a notary public. Ask to be sworn under oath. You must be sworn under oath by a person authorized to do so (such as a county clerk or a notary public).
Read More: How to File an Affidavit
Sign the document under oath and in the presence of the person authorized to swear you in. Signing the affidavit under oath affirms the affidavit; it is your personal guarantee (under penalty of perjury) that the document contains the truth.
Notarize the document or have the document signed by the person who swore you in.