This comes from either the “learn something new every day” or blatantly obvious department.
Years ago a very smart attorney told me that a notarized signature was not required for a valid copyright assignment. It is true that § 204(a) Copyright Act states “a transfer of copyright ownership other than by operation of law is not valid unless an instrument of conveyance, or a note or memorandum of the transfer is in writing and is signed by the owner of the rights conveyed…”. There is specifically no requirement of notarizing the signature.
So, I have wondered for years why publishers and others require copyright assignments to be notarized. While researching something else I seem to have found that the answer is right there in § 204(b) of the act which states “a certificate of acknowledgement is not required for the validity of a transfer but it is prima face evidence of the execution of the transfer if (i) in the case of a transfer executed in the United States a certificate is issued by a person authorized to administer oaths within the United States.
Once again I find the Copyright Act of 1976 incredibly illuminating. In essence, it is not a legal requirement that your copyright assignment be notarized, it’s just a very good idea from an evidentiary standpoint. No one ever discusses the validity of copyright assignments except in the context of evidence. So, I conclude that despite the language of § 204(a), copyright assignments need to be notarized.