20 CFR 404.708: How we decide what is enough evidence.

When you give us evidence, we examine it to see if it is convincing evidence. If it is, no other evidence is needed. In deciding if evidence is convincing, we consider whether—

(a) Information contained in the evidence was given by a person in a position to know the facts;

(b) There was any reason to give false information when the evidence was created;

(c) Information contained in the evidence was given under oath, or with witnesses present, or with the knowledge there was a penalty for giving false information;

(d) The evidence was created at the time the event took place or shortly thereafter;

(e) The evidence has been altered or has any erasures on it; and

(f) Information contained in the evidence agrees with other available evidence, including our records.