Summary The purpose of this work is to provide an explanation of the probative assessment of public commercial documents in which the diversity of competing criteria is considered, giving preference to legal parameters derived from the purposes of public faith in commercial law. The doctrinal categories known as ‘legal evidence’ and ‘free evidence’ are abandoned in order to propose an integrated perspective of the factors involved in the judicial process of assessing evidence and deciding on the facts. It is necessary to maintain a common relationship between, on the one hand, the measures provided for by commercial law in order to achieve the safe and efficient development of traffic and, on the other hand, the adjudication of facts in proceedings in which issues relating to commercial acts, contracts and transactions are discussed.