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Should polygraphs be admissible in court?
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Polygraphs diminish the jury's role

The trial by jury is a bedrock of many Western legal systems. Lie detectors diminish the role of the jury in the legal process.


Many legal systems operate on the founding principles of a trial by jury. In these cases, the defendant is entitled to be tried in front of a jury of their peers. This jury will be the sole body that determines guilt beyond reasonable doubt.

The Argument

Lie detectors, by nature, undermine the fundamental principles of a trial by jury. They diminish the jury’s role in determining guilt. The jury would likely give too much credence to a lie detector result and overlook other strands of evidence presented.

Counter arguments

Assuming that a jury can’t understand that lie detectors are not infallible and would not use them to supplement a decision but as the basis of the legal decision undermines the intelligence of the average citizen. [1] Juries are capable of understanding that lie detectors should be used as a supplement, not the basis, for a case. They can be trusted to carefully consider the evidence presented, of which a polygraph test is only one, potentially fallible part.



[P1] The jury is assigned the task of determining guilt, not a lie detector. [P2] If lie detector tests were admissible in court, they would undermine the principles of a trial by jury. [P3] Therefore, they should not be admissible in court.

Rejecting the premises

[Rejecting P1] The jury would still be in charge of determining guilt. [Rejecting P2] The polygraph test results would just be another piece of evidence. It would not form the basis of a guilty verdict, but nor would it be dismissed. [Rejecting P3] Lie detectors are a useful tool for establishing deceit. Therefore, they should be used, alongside other legal tools to measure deceit, and be admissible in the court of law.


This page was last edited on Monday, 20 Jan 2020 at 10:14 UTC

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