Troy Davis and the Polygraph

Troy Davis

Lawyers for Troy Davis, who faces execution by lethal injection at 19:00 hours Eastern time today for the 1991 slaying of an off-duty Savannah police officer, are seeking a polygraph test in a bid to persuade the Georgia Board of Pardons and Paroles to stay the execution.

The Davis case has been the subject of much controversy, as seven of nine non-police witnesses upon whose testimony his conviction hinged have recanted their testimony, with some of the recanting witnesses alleging that police coerced their testimony. No physical evidence connects Davis to the murder, and it seems that Georgia is about to execute a man concerning whose guilt considerable reasonable doubt exists, and who indeed may be innocent.

As has long pointed out, polygraph “testing” has no scientific basis, and polygraph results are evidence of nothing. Yet it is understandable that with appeals exhausted, Davis’s legal team would grasp at this straw.

If Davis is granted permission to submit to a polygraph test, several points are worth bearing in mind:

  1. Polygraphy has an inherent bias against truthful persons, because the more candidly one answers the so-called “control” questions, and as a consequence, feels less anxiety when answering them, the more likely one is to wrongly fail. Moreover, Davis’s guilt or innocence aside, one can reasonably expect him to be highly sensitized to the relevant questions (the ones about the murder), if only because his life depends on them. If Davis fails the polygraph, it is not evidence of guilt.
  2. Despite polygraphy’s bias against the innocent, liars can easily pass using simple countermeasures that polygraph operators have no demonstrated ability to detect. If Davis passes the polygraph, it is not evidence of innocence.
  3. If the Georgia Board of Pardons and Paroles is so uncertain of Davis’s guilt that it would be willing to consider polygraph results, then regardless of the outcome, the Board has enough doubt that it should commute Davis’s death sentence.

UPDATE: Georgia prison officials have rejected Davis’s request to submit to a polygraph examination.

Comments 1

  • Last week polygraph test gave result on me: “Deception 99%”.

    But the truth is I was loyal and whenever the technician asked “did you have sex with anyone else other than your husband?”, it reminded me of how he cheated me and landed me ruthlessly in trouble and STDs and my body responses are “more” when I say “no” truthfully than when I say a lie “no” for question like “ever you said lie to save someone” (because this is immaterial and petty for me).

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