Jeremy Bentham

By the time Bentham turned his interest to the subject, late in the eighteenth century, most components of modern evidence law had been assembled. Among common-law doctrines regarding evidence there were, however, principles that today are regarded as bizarre; thus, a well-established (but now abandoned) rule forbade the parties to a case denied the right to testify to facts that would prove their innocence.

Although extreme in its irrationality, this proscription was in other respects quite typical of the law of evidence. Much of that law consisted of rules excluding relevant evidence, usually on some rational grounds. Hearsay evidence was generally excluded because absent persons could not be cross-examined. Yet such evidence was mechanically excluded even persons could not appear in court (for example, because they were dead).

The morass of evidentiary technicalities often made it unlikely that the truth would emerge in a judicial contest, no matter how expensive and protracted. Reform was frustrated both by the vested interests of lawyers and by the profession’s reverence for tradition and precedent. Bentham’s prescription was revolutionary: virtually all evidence tending to proof outweighed its value, confessions to a Catholic priest, and a few other instances.

One difficulty with Bentham’s nonexclusion principle is that some kinds of evidence are inherently unreliable or misleading. Such was the argument underlying the exclusions of interested-party testimony and hearsay evidence. Bentham argued that the character of evidence should be weighed by the jury: the alternative was to prefer ignorance to knowledge. Yet But then, why not protect conversations between social workers and their clients, or parents and children?

Despite concerns such as these, the approach underlying modern evidence law began to prevail soon after Bentham’s death: relevant evidence should be admitted unless there are clear grounds of policy for excluding it. This clear-grounds proviso allows more exclusions than Bentham would have liked, but the main nonexclusion principle, demoted from a rule to a presumption.