The "Rule" against Inference on Inference
The "Rule" against Inference on Inference
Courts have occasionally proclaimed that it is illegitimate to base an inference on inference, that inferences cannot be piled on top of each other, and that evidence whose relevance and probative value depend on such pyramided inferences is inadmissible. See, e.g., People v. Atley, 392 Mich. 298, 220 N.W.2d 465, 473, 473-474 (1974). However, John Henry Wigmore long ago condemned this supposed prohibition against the pyramiding of inferences and, despite occasional aberrations, it is almost universally acknowledged that he was correct. The most recent edition of Wigmore's treatise makes the point in the following much-quoted language:
It was once suggested that an inference upon an inference will not be permitted, i.e., that a fact desired to be used circumstantially must itself be proved by testimonial evidence, and this suggestion has been repeated by several courts and commentators and sometimes actually has been enforced.There is no such orthodox rule; nor can there be. If there were, hardly a single trial could be adequately prosecuted. For example, on a charge of murder the defendant's gun is found discharged. From this we infer that he dischraged it, and from this we infer that it was his bullet that struck and killed the deceased. Or the defendant is shown to have been sharpening a knife. From this we argue that he had a design to use it upon the deceased, and from this we argue that the fatal stab was the result of this design. In these and innumerable daily instances we build up inference upon inference, and yet no court (until in very modern times) ever thought of forbidding it. All departments of reasoning, all scientific work, every day's life and every day's trials proceed upon such data.
1A John Henry Wigmore, EVIDENCE IN TRIALS AT COMMON LAW § 41 at 1106-1111 (P. Tillers rev. 1983) (footnotes omitted).
But cf. The Tenth Circuit Makes Pretty Good Sense of the Inference-upon-Inference Rule (July 31, 2005) where the blogger states, inter alia, that "the 10th Circuit has suggested that the inference-upon-inference rule is not a prohibition but a signpost that should warn courts, particularly in criminal cases, against allowing juries (or, presumably, judges) from reaching factual conclusions that are too weakly supported by evidence. ... Although the 10th Circuit didn't get absolutely everything right -- the strength of an inference based on a series of inferences is not as dependent on the number of inferences as the 10th Circuit imagines -- there is much to be said for the approach that the 10th Circuit takes. The 10th Circuit's approach tells judges that when evaluating the strength or sufficiency of evidence (at least in criminal cases) they must decompose the foundation of a final inference into a series of inferences upon which such a final inference rests and judges must then assess the strength or force of the entire chain (I would say "complex") of inferences. There is wisdom -- and valuable inferential discipline -- in this approach: the existence of pyramided inferences is not a myth."
