The Perils of Ad Verecundiam

Efrem Zimbalist, Jr. - Not an FBI Agent But He Played One on Television

Efrem Zimbalist, Jr. – Not an FBI Agent But He Played One on Television

WC has written several times about logical fallacies and the risks they present. Our friends at the Federal Bureau of Investigation have provided us with an excellent illustration of the Argument from Authority fallacy, Ad Verecundiam, recently.

The Argument from Authority fallacy runs like this:

A says P about subject matter S.
A should be trusted about subject matter S.
Therefore, P is correct.

Under the rules of formal logic, the second premise is not accepted as valid, as it amounts to an unfounded assertion that leads to circular reasoning. It enables the proponent to define person or group A into inerrancy on any subject matter.

For decades, FBI forensic lab examiners have appeared in state and criminal court cases claiming that they could identify hairs with very high degrees of confidence. “I’m 100% certain.” Stripped of formality, the credentials of the FBI experts could be summarized, “I’m from the FBI; trust me.”

Jurors, brainwashed influenced by decades of exposure to television shows like The F.B.I., which painted the federal agency as an infallible, flawless super hero, accepted uncritically FBI crime lab testimony. The sloppy science in shows like C.S.I.: Wherever have perpetuated the problem. As a one-time criminal defense attorney, WC can tell you it was maddening to have a guy in a black suit – they always wore black suits – tell the jury that the hair found on the scene matched your client’s hair “100%” based upon his – they were always guys – years of experience and testimony in hundreds of other cases. That’s not science, folks; that’s the logical fallacy of argument from authority.

Now it is all falling apart.You want examples? Santae Tribble, who served 28 years for a murder based on FBI testimony about a single strand of hair, was exonerated in 2012. It was revealed that one of the hairs presented at trial came from a dog. Donald E. Gates served 28 years for the rape and murder of a Georgetown University student based on FBI Special Agent Michael P. Malone’s testimony that his hair was found on the victim’s body. He was exonerated by DNA testing in 2009.

The Tribble case is appalling. The FBI technician who originally testified at Tribble’s 1978 trial, Special Agent James A. Hilverda, said all the hairs he retrieved from the stocking were human head hairs, including the one suitable for comparison that he declared in court matched Tribble’s “in all microscopic characteristics.” In August 2015, Harold Deadman, a senior hair analyst with the D.C. police who spent 15 years with the FBI lab, forwarded the evidence to the private lab and reported that the 13 hairs he found included head and limb hairs. One exhibited Caucasian characteristics. Tribble is black.

The private lab’s DNA tests irrefutably showed that the 13 hairs came from three human sources, each of African origin, except for one — which came from a dog.

It tells you everything you need to know about microscopic hair analysis: two FBI-trained analysts, James Hilverda and Harold Deadman, could not even distinguish human hairs from canine hairs.

As a consequence of the FBI’s error – more correctly, the courts’ and jurors’ willingness to uncritically accept the FBI’s ad verecundiam fallacy – Tribble served 33 years in prison for a crime he did not commit.

He’s hardly alone. The F.B.I. and The Innocence Project have studied 268 trials where an F.B.I. crime lab employee gave hair testimony; in 257 of those cases – that would be 95% of them – the testimony was flawed. 32 of those cases were death penalty trials. 8 of those 257 cases were in Alaska.

Worse still, the F.B.I. “trained” state crime lab examiners in microscopic hair analysis. Who knows how many wrongful convictions came out of the bogus testimony of those state crime lab examiners?

Junk science in the courtroom. Courtesy of the F.B.I. It would be amusing if it weren’t for the damage to innocent people’s lives.






2 thoughts on “The Perils of Ad Verecundiam

  1. I’ve enjoyed your posts on logical fallacies. They’ve been very informative. i do have one concern, however, in that you state “wrongful convictions came out of the bogus testimony,” which makes it sound deliberate, with the examiner/spokesperson purposefully lying or misrepresenting the test results. I think the better descriptor would be “flawed,” or “erroneous” testimony. Without more information we don’t know whether the test was deliberately botched or incompetently performed. Thanks for your consideration.

    • By “bogus,” WC means incapable of rigorous confirmation. In a double-blind test, crime lab experts cannot reliably distinguish dog fur from human hair, let alone distinguish among human hairs. They think they can, and testify they can (with “100% accuracy”), but it turns out were purely incapable of it. Their opinions are cloaked in a claim of “science,” but aren’t science at all.

      Bogus science plagues courtrooms. Lawyers and judges (and juries) aren’t equipped to distinguish the real stuff – competent DNA testing – from the fake stuff – “lie detectors” and bite marks analysis.

      So, yeah, “bogus” seems to be the right word. If you want, we can call it a dataset with (p <0.05), but WC would then only confuse his readers more.


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