The short answer is usually no: commercial contracts generally do not have to be notarized or certified to be legally binding. A long time ago, it was legally necessary to have many types of contracts notarized certified. Today, however, the law generally requires that few types of documents must be notarized to be legal and valid. The most common area where the authentic deed of signatures is still necessary is that of real estate deeds. Some states also require that real estate transactions be monitored. While most real estate transactions must be notarized, some states provide that, as long as a witness is present at the signing of the contract, this is sufficient. The magic behind the certified signature is that many state courts and all federal courts declare that a notarized signature is automatically authentic in court. For example, Rule 902(8) of the Federal Rules of Evidence in the United States. .