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Lie detector in domestic legal realities
What do a lie detector and criminal procedure in Ukraine have in common? While pop culture and American television series often portray the polygraph, or so-called “lie detector,” as an indisputable tool for exposing lies, in reality, its use in Ukrainian criminal procedure remains a little-noticed and controversial topic. Although the current Criminal Procedure Code of Ukraine does not explicitly permit the use of a polygraph, it also does not explicitly prohibit it. Such regulatory uncertainty has led to a situation where polygraphs are actively used in internal personnel procedures of law enforcement agencies, but their evidentiary value in criminal proceedings remains limited.
Recent years have seen the approval of guidelines on the use of polygraphs in the structures of the Ministry of Internal Affairs, the Ministry of Defence, the Security Service of Ukraine, the National Guard, and prosecutor’s offices, among others. In particular, according to the Ministry of Internal Affairs’ Order No. 920 of November 13, 2017, a polygraph is defined as a specialised psychophysiological device that registers at least five indicators of physiological response to psychological stimuli without harming the person.
Is a polygraph, as a means of proof, an innovation or “inappropriate creativity”?
The use of a polygraph at the stage of pre-trial investigation, particularly during interrogation, is a manifestation of the introduction of innovative technologies not only in the forensic component of modern science but also in procedural law. However, the effectiveness of such use largely depends on the professionalism of the polygraph examiner and the correctness of the interpretation of the results. After all, physiological indicators themselves are only indicative, not absolute, data, meaning that the information obtained during the test is probabilistic and indicative, and does not establish facts with legal certainty.
To lend the study’s results evidentiary value, a polygraph must be used as part of a forensic psychophysiological examination, based on a relevant resolution by the investigator, prosecutor, or a ruling by the investigating judge or court, depending on the stage of the proceedings. The expert’s opinion based on the results of such an examination is a procedural source of evidence.
Technical component of the process
Today, the standard for equipment is DSTU 8692:2016. The only polygraph that meets this standard is the RUBICON model, which is actively used by the Kyiv Scientific Research Institute of Forensic Expertise, the State Bureau of Investigation, the National Police, and other organisations. A professional polygraph examination consists of three main stages: a pre-test interview, the examination itself, which involves registering indicators, and the analytical processing of polygraph results based on the examination’s findings. Modern devices record heart rate, blood pressure, respiration, skin conductivity, and other vital parameters in real-time. Based on a comparison of responses to control and relevant questions, the polygraph examiner concludes the truthfulness of the answers. Unfortunately, polygraph results depend on the subjective interpretation of the polygraph examiner, which reduces their objectivity. Stress susceptibility, physiological characteristics, or chronic illnesses can distort the results, even if the person is being truthful. This creates a significant risk of drawing false conclusions that may impact the course of the pre-trial investigation.
It is essential to adhere to the principle of voluntariness. According to Article 28 of the Constitution of Ukraine, no person may be subjected to research without his or her written consent. A polygraph examination cannot be equated with an investigative action, such as interrogation, so any arguments by law enforcement officers regarding the mandatory nature of the examination should be viewed critically. That is why the presence of a lawyer during the interrogation of a person, even if they are a witness, can help avoid such manipulations by the pre-trial investigation body.
What does the court practice say about this?
Court practice shows a “cautious” attitude towards the polygraph. For instance, some court decisions demonstrate a gradual recognition of the significance of polygraph examination results. In case No. 301/943/19, the Irshava District Court of Zakarpattia Region recognised the conclusion of a forensic psychological examination with a polygraph as a valid source of evidence. However, in case No. 676/7835/19, the Khmelnytsky Court of Appeal emphasised the absence of direct authorisation for the use of a polygraph in criminal proceedings and rejected its results as evidence. In its decision, the Appeals Chamber of the High Anti-Corruption Court in case No. 757/13635/17-k stated that “polygraph indicators are only probable and indicative.” A similar position can be seen in the rulings of the Supreme Court, particularly in cases No. 621/1308/18 and No. 234/4850/17.
In other words, a polygraph can only be used as an auxiliary tool to supplement other evidence. Its results have limited evidentiary value, as the opposing party can always appeal to the hypothetical nature of the conclusions of such a study.
International experience of using a “lie detector”
International practice is also ambiguous. In more than 70 countries, polygraphs are used as an auxiliary tool, but the United States is the leader. There, its use is regulated at both the federal and state levels, for example, under California Law No. 351.1 of 1983. In some states, the polygraph is explicitly provided for in the procedural law in the investigation of various “sensitive” categories of criminal offences, such as sex crimes. However, even though polygraphs are more widely used at the state level, their results are often not recognised as evidence in court, but are used solely for preliminary truthfulness assessments.
Conclusions
Thus, although the use of a polygraph appears quite impressive and innovative on screens, it cannot be considered a sufficiently effective procedural tool in criminal proceedings under the current CPC of Ukraine. Its legal uncertainty and the probabilistic nature of the results make it impossible to use them as evidence.
Authors:
- Kristina Kolchynska, Counsel at Criminal Law practice at GOLAW, Attorney at Law
- Marko Kotiv, Paralegal at Criminal Law practice at GOLAW