An affidavit is a written statement or declaration of facts sworn or affirmed by oath and signed before a notary public. Affidavits are used as evidence in court.
There are some instances in a personal injury case where affidavits are typically used. At the earliest stages of an injury case, sometimes a written statement of facts can be obtained from witnesses to the incident which gave rise to the injury. For example, in a case involving disputed claims on the color of a traffic signal, a lawyer may get affidavits from independent witnesses to support the client’s version of the dispute. The affidavits may then be provided to the insurance company so that the insurer can conclude that their insured is at fault and thus liable for the injuries that result from a collision. Why not just get a written (unsworn) statement? That is what usually happens. However, the benefit to an affidavit is that since it is a sworn statement a person can not easily change their story and in the event he does, the affidavit can be used in court to impeach his testimony.
Another example of the use of an affidavit is in a motion for summary judgment. The affidavit may be used to demonstrate to the court that there are issues of fact and that, therefore, deciding the issue of case as a matter of law is inappropriate.