Every signer must be positively identified for a notarization to take place. But signers do not always possess acceptable identification documents. When that happens, an alternative is to use a “credible identifying witness.”
A credible identifying witness is someone who can vouch for the signer’s identity before the Notary — essentially, acting as a human ID card. State rules for credible witnesses vary. Some states require a witness to personally know both the Notary and the signer, others only the signer. In any case, the witness cannot have an interest in the document being notarized. That removes the temptation to misidentify the signer.
Usually, a credible witness must take an oath or affirmation that the signer’s identity is genuine. The witness’ information is taken down in the ID section of the Notary’s journal entry, and the witness usually signs in the ID section of the entry as well.