The Value of Evidence in Law

Northern Ireland Law Quarterly, Vol. 39, p. 167, 1988

12 Pages Posted: 13 Apr 2005

See all articles by Peter Tillers

Peter Tillers

Yeshiva University - Benjamin N. Cardozo School of Law


During the last fifteen years in the United States there has been much talk about uncertainty by two very different groups of scholars. First, legal and non-legal scholars in America and elsewhere have been using formal theories of probability and inference to study uncertainty in factfinding. Second, the collage known as Critical Legal Studies has devoted much of its time and energy to the proposition that legal reasoning and legal doctrines are indeterminate and uncertain.

These two groups of scholars have largely ignored each other. This is not as it should be. Although the two groups seem to be talking about very different kinds of uncertainty, the puzzles that interest these two groups are related. I have suggested elsewhere that the vast and still-burgeoning literature about the interpretation of texts, symbols, and meaning is important to theorizing about the nature of inference from evidence.1 This is because many problems of factual inference involve the job of making guesses about human aims and meanings. Today I want to try building a bridge from the other side of the river. I will argue that theories of factual inference have much to say about theories of legal inference; I will argue that insight into the logic of inference from evidence offers important insights into the logic of legal reasoning; and I will argue that reasoning about facts and reasoning about law are more alike than different.

My thesis is unconventional, and possibly even startling. It amounts to the claim that law is a fact and that all sound law rests on evidence. This claim is not as bizarre as it may seem. I am not arguing that it is possible to be certain of the meaning of law. I am making the much more modest claim that there are better and worse ways of guessing about legal questions; that legal reasoning is a way of guessing about legal questions; and that guessing about legal questions is in many ways like guessing about factual questions.

There was a time - so we are told - when not only facts were facts. There was a time when law was also a fact; there was a time when the legislator, if he existed at all, thought that his job was to discover the law rather than invent it. However, this vision of law as discovered rather than legislated has passed away; we now generally believe that law is legislated rather than merely discovered.

Our vision of the nature of facts has also undergone a profound transformation. There was a time when facts, like the law, simply awaited discovery. If we can believe what some legal historians tell us,2 the rules of evidence and proof were not always designed to facilitate the weighing of factual probabilities. Instead, the law once took the view that evidence, when appropriately packaged and processed, established the truth beyond any doubt.

This sort of theory of evidence and proof is dead. The theories of evidence and inference that now dominate the law are firmly planted in the so-called rationalist tradition of evidence scholarship, a tradition that has been masterfully described by William Twining.3 In that tradition, it is axiomatic that all knowledge of facts is merely probable and always uncertain. We believe that the law of evidence may reduce the frequency of errors in factfinding, but we also believe that factual certainty is unattainable and that no matter how much evidence we have or how careful we are, we can always make mistakes about the facts.

I believe that certainty about any thing is unattainable. Therefore, by saying that law is a fact I am not saying that there is a technique that will restore our faith in our ability to resolve difficult legal questions in a positively correct way that is free of all doubt. All hard cases may have a right answer but they do not have a clear right answer. I am only arguing that the logic of our reasoning about legal uncertainty is much like the logic of our reasoning about factual uncertainty.

Suggested Citation

Tillers, Peter, The Value of Evidence in Law. Northern Ireland Law Quarterly, Vol. 39, p. 167, 1988, Available at SSRN:

Peter Tillers (Contact Author)

Yeshiva University - Benjamin N. Cardozo School of Law ( email )

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