What Is Evidence?

1
Is legal evidence that which is legally accepted as evidence?

Perhaps.

But this definition is not helpful if one is a judge or lawyer who is attempting to determine whether some matter is or is not evidence and wishes to have a criterion for resolving the question. Furthermore, is not the yearning for a definition of evidence a yearning for an understanding of the law's view of the sorts of matters that properly increase human knowledge about possible fact?

Wigmore's definition of evidence, though not wholly vacuous, has a largely question-begging character for the judge or lawyer who wants a standard that distinguishes evidence from other matters affecting judgment about factual possibilities and hypotheses. Wigmore said that legal evidence is

Any knowable fact or group of facts, not a legal or a logical principle, considered with a view to its being offered before a legal tribunal for the purpose of producing a persuasion, positive or negative, on the part of the tribunal, as to the truth of a proposition, not of law or of logic, on which the determination of the tribunal is to be asked.

Wigmore TREATISE Section 1(c) (P. Tillers rev., 1983).

2

Is legal evidence anything that offers some support for the truth or falsity of a legally-material factual hypothesis?

Perhaps.

But this definition seems to mix up -- "conflate" -- the distinct notions of evidence and relevance. Relevant evidence is evidence that increases or decreases the probability of a materially-legal fact. See, e.g., Federal Rule of Evidence 401. This definition presupposes that some evidence may be irrelevant. Hence, once cannot easily say that evidence is evidence only if it is (to some slight degree) relevant or probative.

3

Does legal evidence encompass any matter that can affect the probability of a legally-material factual hypothesis?

Perhaps.

But this definition turns argument into evidence. Conventional dogma holds that argument is not evidence.

A nice question is whether testimony about mathematical principles is genuine testimony and whether the information conveyed by such "testimony" is "evidence." See I Bentham, RATIONALE OF JUDICIAL EVIDENCE 19-20 (Mill ed. 1827) (Bentham had the notion that questions "even in mathematics are questions of evidence"; "[t]he facts, the evidentiary facts, are feigned; but the question concerning the inference to be drawn in each instance from the feigned existence of the evidentiary facts to the existence of the facts sought - the question whether, in the way of analogy, the supposed evidentiary facts afford a sufficient ground for being persuaded of the corresponding existence of the principal facts is not the less a question of evidence"). Compare Stoebuck, Relevancy and the Theory of Probability, 51 Iowa L. Rev. 849, 851 (1966) (discussing People v. Risley, 214 N.Y. 75, 108 N.E. 200 147 N.Y.S. 1132 (1915) (in which mathematician testified as to probability that letters typed on typewriter in question would have eleven specific peculiarities).

4

As can be seen from the quotation in paragraph 1 above, Wigmore attempted to exclude matters that function as argument, persuasion, and logic from the definition of legal evidence.

Perhaps.

But this approach also presents difficulties. For example, the law speaks of and sanctions the use of "expert evidence." Yet some expert evidence concerns the principles a trier of fact should or might use to draw conclusions, or inferences, from other evidence.

5

One might try to limit "evidence" to matters that can be apprehended by the senses -- by eyesight, hearing, and so on.

But this approach also presents difficulties.

The principal difficulty is that almost all evidence presented in the courtroom is at least one step removed from "direct" sensory perception. For example, almost all evidence is presented by witnesses who testify about matters that they may have perceived. Yet such testimony is often considered "evidence."

It will not do to say that the trier of fact at trial perceives the words and demeanor of witnesses. If this were sufficient reason to call a person a witness and the information that (s)he conveys "evidence," all pronouncements and demeanor of all authorized actors in the courtroom should count as evidence. But many of the statements that, e.g., trial counsel and court reporters make do not qualify as "evidence."

The theory that true witnesses report their sensory perceptions, and other courtroom actors do not also does not work seamlessly: Many actors who are counted as witnesses report their own inferences, or conclusions, from either their own perceptions -- or from the perceptions or conclusions of yet other actors.

***

So,gentle Reader, WHAT IS LEGAL EVIDENCE?

I have a guess. My guess is as good as any other. And it may be better than any other guess.

***

My guess begins with an observation. The observation is that most of the modern (occidental) world lacks an ontology. To wit: much or most of the modern world does not have a theory about the fundamental nature of being. This is an important observation or premise.

Bereft of an ontology - a theory about the underlying structure of the world -- modern (wo)man cannot identify privileged sources of information about the world. So (wo)man is left only with a negative concept of evidence: evidence is any matter that can point beyond itself to some other matter.

In the heyday of British empiricism -- which in fact was fairly recent in some quarters of the American academic world -- it was possible to restrict "evidence" to the material perceptible sources of sensory data. But the widespread collapse of rigorous empiricism -- or, in any event, the collapse of an authoritative consensus about the theory of being and knowledge known as empircism -- even this restriction is no longer possible; many people now believe that matters such as wiring in the brain are potential sources of information and evidence.

The net effect of these developments is that it is practically impossible to define evidence. What can be said about "evidence" is that it has an intimate association with "inference." "Inference" is the drawing of a proposition about the world from some other proposition about the world. "Evidence" is any matter -- and "evidence" can be practically any matter -- "evidence" is any matter that can serve as a basis for an inference about some other, or separate, matter. The modern concept of "evidence" is the byproduct of the theory of being and knowledge that supports the modern notion of "inference." And "inference" is no longer limited to the extraction of conclusions from a sensory or material foundation -- although it must be supposed that the premises of any inference must somehow exist in or be compatible with the material foundations or dimensions of the world.

It is true, of course, that the law refuses to characterize some information as "evidence" and it refuses to characterize some human sources of information as "witnesses." For example, trial counsel are not ordinarily "witnesses" and their statements are not normally "evidence." But the reasons for these characterizations are very probably rooted in institutional considerations (about the appropriate design of the adversary system) rather than in beliefs or theories about the nature of the sources and foundations of human knowledge of the world. The same sort of explanation probably holds for other exclusions from the concept of evidence -- for the exclusion, for example, of sources of information about (uncertain) legal norms. Cf. P. Tillers, The Value of Evidence in Law, 39 Northern Ireland Quarterly Law Review No. 2 (1988)