by which every witness is privileged not to accuse himself, can neither of them be entirely disregarded. They are believed both to be preserved to a reasonable extent, and according to the true intention of the rule and of the exception to that rule, by observing that course which it is conceived courts have generally observed. It is this:
When a question is propounded, it belongs to the court to consider and to decide whether any direct answer to it can implicate the witness. If this be decided in the negative, then he may answer it without violating the privilege which is secured to him by law. If a direct answer to it may criminate himself, then he must be the sole judge what his answer would be. The court cannot participate with him in this judgment, because they cannot decide on the effect of his answer without knowing what it would be; and a disclosure of that fact to the judges would strip him of the privilege which the law allows, and which he claims. It follows necessarily then, from this statement of things, that if the question be of such a description that an answer to it may or may not criminate the witness, according to the purport of that answer, it must rest with himself, who alone can tell what it would be, to answer the question or not. If, in such a case, he say upon his oath that his answer would criminate himself, the court can demand no other testimony of the fact. If the declaration be untrue, it is in conscience and in law as much a perjury as if he had declared any other untruth upon his oath; as it is one of those cases in which the rale of law must be abandoned, or the oath of the witness be received.
The counsel for the United States have also laid down this rule according to their understanding of it; but they appear to the court to have made it as much too narrow as the counsel for the witness have made it too broad. According to their statement a witness can never refuse to answer any question unless that answer, unconnected with other testimony, would be sufficient to convict him of a'crime. This would be rendering the rale almost perfectly worthless. Many links frequently compose that chain of testimony which is necessary to convict any individual of a crime. It appears to the court to be the true sense of the rule that no witness is compellable to furnish any one of them against himself. It is certainly not only a possible but a probable case that a witness, by disclosing a single fact, may complete the testimony against himself, and to every effectual purpose accuse himself as entirely as he would by stating every circumstance which would be required for his conviction. That fact of itself might be unavailing, but all other facts without it would be insufficient. While that remains concealed within his own bosom he is safe; but draw it from thence, and he is exposed to a prosecution. The rule which declares that no man is compellable to accuse himself would most obviously be infringed by compelling a witness to disclose a fact of this description.
What testimony may be possessed, or is attainable, against any individual the court can never know. It would seem, then, that the court ought never to compel a witness to give an answer which discloses a fact that would form a necessary and essential part of a crime which is punishable by the laws.
To apply this reasoning to the particular case under consideration: To know and conceal the treason of another is misprision of treason, and is punishable by law. No witness, therefore, is compellable by law to disclose a fact which would form a necessary and essential part of this crime. If the letter in question contain evidence of treason, which is a fact not dependent on the testimony of the witness before the court, and, therefore, may be proved without the aid of his testimony; and if the witness were acquainted with that treason when the letter was written, he may probably be guilty of misprision of treason, and, therefore, the court ought not to compel him to answer any question, the answer to which might disclose his former knowledge of the contents of that letter.
But if the letter should relate to misdemeanor and not to the treason, the court is not apprized that a knowledge and concealment of the misdemeanor would expose the witness to any prosecution whatever. On this account the court was, at first, disposed to inquire whether the letter could be deciphered, in order to determine from its contents how far the witness could be examined respecting it The court was inclined to this course from considering the question as one which might require a disclosure of the knowledge which the witness might have had of the contents of this letter when it was put in cipher, or when it was copied by himself; if, indeed, such were the fact. But, on hearing the question more particularly and precisely stated, and finding that it refers only to the present knowledge of the cipher, it appears to the court that the question may be answered without implicating the witness, because his present knowledge would not, it is believed, in a criminal prosecution, justify the inference that his knowledge was acquired previous to this trial, or afford the means of proving that fact.
The court is, therefore, of opinion that the witness may answer the question now propounded.
The gentlemen of the bar will understand the rale laid down by the court to be this: It is the province of the court to judge whether any direct answer to the question which may be proposed will furnish evidence against the witness. If such answer may disclose a fact which forms a necessary and essential link in the chain of testimony, which would be sufficient to convict him of any crime, he is not bound to answer it so as to furnish matter for that conviction. In such a case