Sunday, June 26, 2005

Polygraphy and the Fifth and Sixth Amendments

We yield to no one in our distaste for polygraph evidence. It should all be excluded as unreliable and prejudicial, and also because it encroaches on the jury's function. But we're wondering about the constitutional legitimacy of another basis that courts have sometimes used to exclude it, most recently in United States v. Ross, No. 04-2124 (7th Cir. June 20, 2005). The notion in question is that polygraph tests taken by criminal defendants on their own initiative and without prior notice to the prosecution should be excluded from evidence because they represent a one-way street. If the defendant happens to pass the polygraph, the defendant unveils the results. But if the defendant flunks it, the results never see the light of day.

Of course, the same might be said of expert evidence developed by criminal defense counsel in general. If it's exculpatory, it's offered, and if it's inculpatory, it's buried. But polygraph evidence might be thought a special case, because of an asymmetry in the power of prosecutors and defense counsel to develop it. By virtue of the constitutional prohibition against compelled self-incrimination, the prosecution cannot normally administer a polygraph to a criminal defendant over the defendant's objection. It might be thought unfair, to admit evidence of a certain type, if the defendant enjoys a unilateral right of veto over all evidence of the same type.

But wait a minute. Not only does that "unfairness" argument ring of "sporting contest" theories of litigation that seem particularly out of place in criminal proceedings; it also proves too much, because in general, the Constitution vests in criminal defendants the unilateral right to withhold their testimony altogether, or to offer it if they choose. That is, it gives them precisely the same kind of unilateral veto that courts find unpalatable in the polygraph context.

It's not our field, but we assume that offering an exculpatory polygraph would waive the defendant's Fifth Amendment privilege, thereupon obviating any constitutional impediment to the prosecution's ability to take a polygraph of its own (at least any constitutional impediment resting on the ban against compelled self-incrimination). If that's right, then any remaining procedural difficulties with a prosecution polygraph would be of less than constitutional proportions (is that right, or are there other constitutional issues?), and could perhaps be solved (e.g., by an adjournment of trial, or through a pretrial notice requirement).

Would a court's refusal to help solve those less-than-constitutional procedural obstacles violate the right of the accused under the Sixth Amendment to present a defense? That argument would probably be an uphill battle in light of United States v. Scheffer, 523 U.S. 303 (1998). But the holding in Scheffer rested in part on the Court's deference to a flat ban on polygraph evidence under the Military Rules of Evidence. Reasonable jurisdictions could differ, said the Scheffer Court, on whether polygraph evidence is ever sufficiently reliable to be admissible. Let us take that idea seriously for a moment. The Federal Rules of Evidence, of course, impose no per se bar against polygraph testimony; not an explicit one, anyhow. A total ban remains in place under decisional law in some circuits. But in most, polygraph testimony is theoretically admissible under Daubert, if some trial court, in the exercise of its sound discretion, should chance to find it scientifically reliable in the particular case. And in a jurisdiction whose evidentiary rules at least permit a court to find a species of evidence scientifically reliable, the argument that its exclusion infringes the right to present a defense seems correspondingly stronger.

In our belief, the question is somewhat academic, because in our belief, polygraph testimony can and should be legitimately excluded on other grounds, without any reliance on the "one-way street" argument. But in the interests of intellectual coherence, as well as judicial candor and precedential clarity, maybe it would be better if the courts rested their exclusionary polygraph decisions on those other grounds, rather than on a "one-way street" argument that doesn't quite seem to work, and which may also be constitutionally suspect.


Post a Comment

<< Home

Fed. R. Evid. 702: If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise, if (1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case.