The federal court of appeals that affirmed Conrad Black’s criminal conviction did so without ever addressing the constitutional argument that was central to his case. The Court achieved this by invoking a legal doctrine of questionable relevance to Black’s case.

Black, along with other defendants, had been convicted of violating a federal statute that makes it a crime to “deprive another of the intangible right to honest services.” The defendants maintained at trial that they did nothing more than re-characterize management fees as non-competition payments so as to take advantage of Canadian tax laws.

On appeal defendants maintained that the trial court erred by refusing to instruct the jury that it was required to find that the company to which the defendants owed the duty of honest services (Hollinger) had actually suffered financial injury. The government responded that no such showing was required under the honest services fraud statute. If this were so, the defendants replied, then the statute was so amorphous as to be unconstitutional.

The Court began its decision by adopting the government’s position that financial injury was not a required element of the honest services fraud statute. At this point, the Court should have addressed the defendant’s constitutional claim.

But it did not. Observing that some evidence of financial injury to Hollinger had been introduced at trial (despite the absence of a jury instruction on the issue), the Court concluded that the jury would have convicted Black had it been required to make a finding of financial injury. For this reason, according to the Court, it was not required to address the constitutional challenge since under Black’s own, narrower construction of the statute, he would have been found guilty.

What the Court was relying on here is known as the “harmless error rule” — which permits a conviction to stand if an appellate court determines that the error at trial had no consequence on the outcome of the case. Brought to America from England in the early 20th century, the rule was endorsed by American legal reformers as a means of avoiding the costs and inefficiencies of retrying cases for trivial errors at trial.

In the 1960s the Supreme Court expanded the harmless error rule to include violations of constitutional rights; and while the Court also recognized a category of constitutional rights which required automatic reversal and hence were not subject to the harmless error rule, that category has contracted substantially over the last several decades. In other words, at the same time that the federal courts, beginning in the 1960s, began to expand the scope of constitutional rights, those same rights were quietly defused by a broadening use of the harmless error rule.

Beyond its general impact on constitutional rights, the harmless error rule, when un-cabined, usurps the traditional and constitutionally mandated function of the jury — that is, investigating the truth of a case by observing firsthand the testimony and demeanor of witnesses. The courts of appeal become, in effect, uber-juries which are no longer reviewing cases for errors of law but rather are making determinations of fact for the first time on appeal. To give this power to appellate judges defies the social and political objectives that compelled the Founders to make the jury system a constitutional mandate.

Let us apply this to the specifics of the case against Black: While the government argued, with some evidentiary support, that Black injured Hollinger by paying himself management fees to which he was not entitled, the government’s chief witness on this point, David Radler, Hollinger’s president and chief operating officer, rebutted the government’s theory, testifying that he believed the money received by Black was a management fee to which he was entitled.

For the Court of Appeals to find harmless error under this circumstance — that is, for the Court to find overwhelming evidence that Black was not owed the management fees — would require the Court to discredit Radler’s testimony in its entirety, and to do so without ever having observed that testimony.

Beyond this is a more fundamental objection to the use of the harmless error rule in Black’s case. As noted by several scholars, the harmless error rule is only justified when applied to that category of constitutional rights that serve to guarantee the truth finding function of the jury, such as the right to have the government turn over exculpatory evidence or the right not to have a forced confession admitted at trial.

When the evidence at trial demonstrates guilt beyond a reasonable doubt and when the evidence which was admitted in violation of such rights is of no weight, then the accuracy of the fact finding process is assured and the constitutional violation fails to justify the expense, time, and lack of finality involved in repeating the trial.

But this is not so when the constitutional right in question serves interests other than the accuracy of the jury’s assessment of the facts. The constitutional guarantee against vague and overbroad statutes, meant to give the public the security of knowing what is and what is not criminal conduct, is such a right. Its importance is unrelated to the accuracy of the jury’s fact finding and should not therefore be subject to the harmless error rule.

For the Court of Appeals to hold, as it did in Black’s case, that it need not rule on the constitutionality of the honest services fraud statute because there was enough evidence to conclude that Black had caused financial injury to Hollinger, leaves in place a law that has been widely condemned for its ambiguity and that has been used to imprison individuals for actions that no reasonable person would suspect to be a criminal violation. As to the dangerousness of the statute, take this example:

Critical to the Court’s holding in the Black case was the Court’s statement that “[h]ad the jury believed that the payments … were actually management fees owed the defendants, as the defendants argued, it would have acquitted them.” That statement is indisputably false: the jury instruction was written in such a way that the jury could have concluded that the management fees were owed Black and still found him guilty of honest services fraud.

This means that the judges on the Court, in relying on a false statement to uphold Black’s conviction, violated their fiduciary duty to the judicial system, to the public, and certainly to Black. If this is combined with the holding of certain appellate courts that when public officials violate the honest services fraud statute it is not necessary to prove personal gain, then the members of the Court in Black’s case could be indicted for honest services fraud.

An arbitrary and ridiculous result, no doubt; but an arbitrary and ridiculous result that is possible so long as the courts refuse to restrict the honest services statute or declare it unconstitutional. In its eagerness to convict Black, the Court ignored Edmund Burke’s admonition that the law must be the eternal enemy of arbitrary power, not its servant.

Mr. Rips, who last wrote in these pages “The Appeal of Conrad Black,” is a former clerk to Associate Justice William Brennan of the United States Supreme Court.