While Notaries are prohibited from refusing a notarization without due cause, there are situations in which you are perfectly justified -- and even legally required -- to refuse to complete a notarization.
Among the valid and compelling reasons for which you can refuse a notarization outright: when you have a compelling or reasonable suspicion that the transaction is unlawful, dishonest or improper; when you're uncertain which notarial certificate to use or how to complete it; when you cannot effectively communicate with the signer; the signature to be notarized is yours or the document bears your name or signature; when the notarization would call into question your impartiality; or when you can't positively identify the signer.
In addition, a notarization should be stopped immediately if you suspect the signer is subject to undue influence or is incapable of understanding or acting responsibly.
If you refuse a notarization, note the circumstances in your journal. Indicating why the notarization was refused could help prevent a discrimination lawsuit.
Keep in mind that you cannot refuse a notarization based on the signer's race, nationality, ethnicity, citizenship, religion, politics, lifestyle, gender, sexual orientation or the contents of the document. It would also be considered improper to refuse notarial services based on the signer's status as a non-client or noncustomer.