The witness affidavit form is essentially useful for various legal cases such as for those filing for dissolution of marriage where witnesses are mandatory for the proceeding of the case. The major purpose of this form is to prove residency of the witness to the court under which the legal case is being heard. These are required for both civil and criminal cases but more so for the former. The witness affidavit form must be formulated according to the respective state laws and a lawyer must be consulted for this. This also needs to be stamped by a notary clerk.