Polygraph as evidence in court

Using the polygraph as evidence in court: the role of the lie detector in legal proceedings.

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The use of the lie detector, or polygraph, as a means of proof in court proceedings has been debated by legal professionals and researchers for many years. The question concerns the significance and reliability of polygraph readings and their possible influence on court decisions.

• The Supreme Court of Ukraine has not recognised a polygraph test as evidence in its own right — on the contrary, its rulings point directly to its limitations. In case No. 589/4601/21 (ruling of the Civil Cassation Court of 29.11.2023), the Court stated that an expert conclusion based on a polygraph does not refute the fact that money was received under a written receipt. In case No. 686/12914/16-k (ruling of the Criminal Cassation Court of 06.03.2018), the Court found the defence’s complaints about the refusal to order an examination with a computer polygraph groundless: carrying out particular investigative actions is a right, not an obligation, of the investigator and the court.
• An important aspect is conducting lie detector tests both at the pre-trial stage and in court practice. An examination carried out with a computerised polygraph can provide additional well-founded data for consideration in court cases.
• It is important to note that when polygraph data are used as evidence, high standards of expertise and test administration must be observed. That is why a polygraph examiner’s conclusion cannot be decisive: the court assesses it only together with other evidence.

All these aspects point to a growing interest in using the lie detector as a means of proof. The practice of the Supreme Court shows that polygraph results are not evidence in themselves; they can be taken into account only as additional information together with the other evidence in a case.

Here are a few more details about using the polygraph as evidence in court:

• The polygraph is not 100% accurate. There are a number of factors that can lead to false polygraph test results, such as stress, nervousness or preparing for the test.
• The polygraph cannot be used to prove guilt. It can only show whether a person is lying, but it cannot show that they are guilty of a specific crime.
• Courts are not obliged to accept polygraph test results as evidence. Judges may decide that the test results are not reliable or objective.

Despite these limitations, a polygraph test can be useful for establishing the circumstances of a case — above all at the investigation stage. A polygraph test can help uncover lies that other evidence may not reveal. It can also help rule suspects out of an investigation if they are not lying.

If you are facing a criminal charge, it is important to consult a lawyer and a polygraph examiner to discuss whether a polygraph test could be useful in your situation. A lawyer and a polygraph examiner can assess your case and determine whether the polygraph is a useful tool for protecting your interests.

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