Polygraphs violate the right to not self-incriminate

The argument

This argument holds that polygraph evidence cannot be fitted into a criminal trial without damaging one of the protections the trial depends on, and that the damage occurs whether the test is compulsory or voluntary. The compulsory case engages the right to silence directly. A suspect always has the right to remain silent and not answer a question if the answer they provide could self-incriminate. If the suspect is forced to carry out a lie-detector test, the answers they give to the questions asked could potentially self-incriminate — and the compulsion reaches further than in ordinary questioning, because the test claims to draw its conclusions from the body's responses rather than from what the suspect chooses to say. A protection that allows a person to decline to answer is of little use if declining can be overridden by measurement. The voluntary case fails for a different reason. Suppose a polygraph test were introduced as a voluntary component in legal proceedings. If a suspect refused to take one and the refusal was presented to a jury as evidence, it could affect their decision — an inference drawn against the accused from the exercise of a right. That eliminates the presumption of innocence until proven guilty, because the accused is penalised for declining rather than for anything the prosecution has established. The option is therefore only nominally voluntary: a choice whose refusal carries a cost is a form of pressure. The two cases together close off the alternatives, since a polygraph in court must be either required or offered, and each route damages a different safeguard. However polygraphs were to be used, the argument concludes, they would compromise the basic principles of a legal trial — so lie detectors should not be admissible in court.

Context

Introducing lie-detector tests into court proceedings would represent a clear violation of a suspects right to not self-incriminate.

Premises

Counter-arguments

Polygraph questions that do not deal with the specifics, including where/when the crime took place, who the victim was and the names of other people involved, would not be sufficiently detailed to violate a defendant’s right not to self-incriminate. The burden of proof would still be on the prosecutor to incriminate the defendant and prove beyond reasonable doubt that they committed the crime in question. The polygraph would not provide a lead or link to evidence used in the conviction. However, it would be useful to background information and used to show the defendant’s character in front of a jury. Also, the term "self-incrimination" does not really apply here. The safeguards designed to protect against self-incrimination were supposed to prevent the government from forcing defendants to testify against themselves. They were not designed to prevent law enforcement officers from extracting information from them. Consider a case where someone gets arrested for drink driving. They go to the police station, where the police take their blood. Blood tests reveal that the driver was driving intoxicated. Would this person be able to argue that their right to self-incrimination was infringed because law enforcement used evidence taken from the defendant in their case? No. Lie detector tests function in the same way. They do not violate a defendant's right to not self-incriminate because the state will not get to the defendant to testify. It is simply a mechanism to extract evidence from the suspect, in much the same way as a blood test does.

Rejecting the premises

[Rejecting P1] Polygraphs no more violate an individual's right to not self-incriminate than a blood test or breathalyser reading. [Rejecting P2] They do not violate the design of the Fifth Amendment. Therefore, they should be admissible in court.