New Jersey Proof of Witness of Codicil is a document that is required in the state of New Jersey when an individual wishes to make a change or amendment to an existing will. This document is signed by two individuals who can confirm that the individual making the changes was mentally competent to do so and that the changes were read to them before they signed. The two witnesses must be disinterested, meaning that they are not beneficiaries of the will in any way. There are two types of New Jersey Proof of Witness of Codicil: a signed affidavit from the witnesses, and a notarized affidavit from the witnesses. Both documents must be signed in front of a notary public in order to be valid.