What is the current state of the law in the context of alleged forgery and alleged perjury?

The case of People v. Badgley, 16 Wend. 53, was a case of alleged forgery, where a conviction was based largely on confessions of the defendant. The note alleged to have been forged was destroyed, so that neither the original nor a copy could be produced, and the person whose name was alleged to have been forged was dead, and there was no evidence directly establishing the forgery by the defendant outside of his confession.[193 N.Y. 63]There were, however, a number of facts indirectly tending to establish that he was guilty as confessed. Under those circumstances the court wrote as follows: Full proof of the body of the crime, the corpus delicti, independently of the confession, is not required by any of the cases; and in many of them slight corroborating facts were held sufficient. Here there are a number of facts, and some of them strong and convincing. The highest and best evidence in the power of the prosecutor was produced, and no effort was made by the accused to explain, where explanation was easy and complete upon the assumption of innocence. There is much circumstantial evidence of the forgery of the note, which, in connection with the confessions, brings the mind to a satisfactory conclusion of the defendant's guilta conclusion justified by abundant authority. What was thus said is entirely pertinent, for as was stated in the Jaehne Case, the present statutory enactment embodies what was the prior rule of the common law.

The case of People v. Jones, 123 Cal. 65, 55 Pac. 698, presented for review a conviction of arson. The evidence upon which the defendant had been convicted consisted largely of his confessions. The rule in California requiring evidence in addition to the extrajudicial confessions of the defendant was substantially the same as that which we have been considering, and it was claimed that sufficient additional evidence was lacking. The court in construing this claim lays down the following rule: In the case before us, I think the evidence, though weak and unsatisfactory in particulars capable of more explicit statement, is sufficient to justify the admission of the confessions. The buildings were in fact burned, and the circumstances tended in some degree to indicate that the fire was of incendiary origin, and therefore the confessions were in some degree corroborated.