【Legal Life】Ch5 "If you haven't lied, why fear a lie detector test?" Is it really that simple?

Although Chieh-yun gave detailed and consistent witness testimony, Chun-ming repeatedly insisted during interrogation that he did not realize he had hit anyone while driving, and thus there was no issue of a hit-and-run. However, the prosecutor considered these claims to be mere excuses.

"Whether you knew you hit someone or not isn't something your mouth can reliably decide! A lie detector test is much more practical!" said the prosecutor.
"I admit I hit someone, but at the time I simply didn't know I had hit anyone! I didn't lie, so why should I take a lie detector test?" Chun-ming felt his personal integrity was being insulted, and his tone rose slightly.
"If you haven't lied, then why are you afraid of a lie detector test? If you're innocent, the test can just clear your name! Not daring to take the test must mean you have something to hide!" The prosecutor's voice also grew louder.
"Fine, a lie detector test it is, who's afraid of whom!" Chun-ming retorted, refusing to back down.

In a moment of impulse, Chun-ming agreed to undergo a lie detector test. Yet, just as the test was about to begin, a now-calmer Chun-ming recalled that when he was discussing the case with his attorney earlier, he had skimmed through the Code of Criminal Procedure but seemed to find no provisions regarding lie detector tests...

What is a lie detector test?

Everyone has likely heard of the term lie detector test, but how such a test is conducted remains somewhat unfamiliar. A lie detector test can generally be divided into two parts.

The first half involves Q&A between the polygraph examiner and the examinee. During this stage, the examiner places polygraph equipment—which measures physiological responses such as heartbeat and blood pressure—on the examinee and asks pre-designed questions. As the examinee answers, the polygraph equipment records their physiological responses to emotional changes.

The second half involves evaluation. Professionally trained evaluators compare the examiner's questions and the examinee's physiological responses during their answers to determine which statements carry a "possibility of deception."

In short, a lie detector test is an investigative technique that uses polygraph equipment to record an examinee's physiological responses, which are then used to judge whether their statements are true.

The principles behind lie detector tests

As mentioned above, lie detector tests use an examinee's physiological responses during testing as the basis for determining whether they are lying. But why do people produce physiological responses different from usual when lying?

Human speech is generated by first forming thoughts in the brain and then translating them into words to be spoken. This means that most of the time (except when lying), people speak true to their brain's thoughts, whereas lying is an act of distorting the brain's true thoughts. Because lying is not human nature, ordinary people are more likely to exhibit reactions different from their usual behavior when lying, such as emotional fluctuations like guilt, anxiety, or fear, which in turn affect physiological responses, such as an accelerated heartbeat (enhanced pulse), rapid breathing, or cold sweats.

As for why lying triggers such physiological responses, the reason lies in the human instinct of "avoiding harm." Because people subconsciously know that lying is not a good thing, their bodies prepare in advance for the consequences of "lies being exposed" at the moment of lying. An accelerated heartbeat and increased blood flow supply abundant oxygen, helping the human body exert greater strength than usual to face the consequences of a lie being exposed. Therefore, an accelerated heartbeat and similar reactions commonly accompany lying.

Lie detector tests are investigative techniques designed based on these aforementioned human instinctive responses.

The connection between lie detector tests, the right to silence, and the privilege against self-incrimination

A lie detector test must be conducted through a back-and-forth Q&A between the examiner and the examinee. However, does such a Q&A format infringe upon the examinee's right to silence or violate the privilege against self-incrimination?

Pursuant to Article 95, Paragraph 1, Subparagraph 2 of the Code of Criminal Procedure, a defendant may remain silent during interrogation and is not required to make statements against their own will. This means that when undergoing interrogation, a defendant has the right to remain silent and has no obligation to cooperate with investigators by confessing that they have committed a crime. In other words, investigators are not permitted to force a defendant to make a confession.

Therefore, if a defendant is coerced into undergoing a lie detector test, it raises issues of infringing upon the right to silence and violating the privilege against self-incrimination.

Can the results of a lie detector test be used as evidence?

While lie detector tests are investigative methods that have been practiced for many years in judicial practice, the Code of Criminal Procedure contains no explicit provisions regarding them. Consequently, whether the results of a lie detector test possess probative value exists in a state lacking statutory basis, and legal practice and academic theories are divided on whether to recognize the probative value of lie detector results. Obtaining the examinee's consent prior to the test is a precondition for the test results to be admissible as evidence. However, does obtaining consent prior to the test mean that the test results can invariably be used as evidence?

Many views hold that if a lie detector test meets the following requirements during its administration, the results may be used in trial as evidence to establish the defendant's guilt:

1. The examinee consented to cooperate, and was informed of their right to refuse the lie detector test to alleviate unnecessary pressure.
2. The polygraph examiner must be well-trained professionally and possess extensive experience.
3. The polygraph equipment must be of good quality and in normal operating condition during the test.
4. The examinee's physical, mental, and conscious states must be normal (e.g., testing must not be conducted when the examinee is fatigued).
5. The testing environment must be favorable, free from improper external interference (e.g., prohibiting the presence of the victim).

On the other hand, some views argue that the greatest characteristic of "scientific forensic techniques" is "reproducibility" (regardless of how many times a test is conducted, the results remain the same), such as DNA testing, fingerprint comparison, and drug testing. However, the subject of a lie detector test is a "person" rather than an "object." Therefore, even if the equipment, examiner, and testing environment are identical, because an examinee's psychological and physiological states cannot be completely identical across different testing sessions, it differs from fingerprint comparison and drug testing and lacks reproducibility. Furthermore, humans possess instincts for learning and avoiding danger; undergoing multiple lie detector tests makes a person less prone to nervousness, and the aforementioned physiological responses will become less pronounced or even indistinguishable from normal states. Consequently, it is difficult to recognize the probative value of lie detector results in judicial trials.

Nevertheless, entirely denying the probative value of lie detector results would hinder the discovery of substantive truth; yet, uniformly recognizing lie detector results as having probative value would inadequately protect the defendant (examinee). To balance the discovery of truth with the protection of human rights, another view suggests that "lie detector results possess probative value, but they shall not be adopted as the sole basis for a guilty verdict." In other words, corroborating evidence is still required.

How should one handle a lie detector test?

As mentioned above, lie detector tests are investigative methods that lack explicit provisions in the Code of Criminal Procedure but have been practiced for many years. Amidst a growing awareness of human rights, judicial practice has placed stricter limitations on whether lie detector results possess probative value. Therefore, when encountering a lie detector test, we should understand how to respond.

• We can refuse to undergo a lie detector test
  Because a lie detector test requires the examinee's cooperation to be conducted, forced polygraph testing would infringe upon the examinee's personal liberty and demean their human dignity. From the standpoint of constitutional human rights protection, unless explicitly authorized by law, neither judicial police officers, prosecutors, nor even courts may conduct forced lie detector tests. Since our country currently lacks such statutory authorization, strictly speaking, investigators or courts cannot conduct forced lie detector tests, meaning we can refuse to undergo them.
  From another perspective, pursuant to the presumption of innocence, proving a defendant's criminal suspicion and shouldering the burden of proof is the prosecutor's job. The defendant has no obligation to assist the prosecutor, let alone the responsibility to prove their own innocence. Therefore, saying, "If you haven't lied, why fear a lie detector test? If you're innocent, the test can just clear your name!" can be described as sophisticated rhetoric. While it sounds reasonable at first hearing, because a defendant has no obligation to "prove their own innocence" in the first place, they certainly do not have to undergo a lie detector test against their own will. However, it is still best to provide some rationale when refusing a lie detector test—such as distrusting the results of lie detector tests or having a naturally nervous disposition—to avoid deepening the investigators' suspicions.
  
• If you consent to a lie detector test, you must pay attention to the following
  Although judicial judgments have placed greater restrictions on using lie detector results as evidence, because courts have historically focused on multiple outcomes of lie detectors while paying little heed to the process, several factors affecting the accuracy of lie detector tests are frequently ignored by courts. These include: whether the examinee was informed of the right to refuse the test to alleviate unnecessary pressure; whether the examiner was well-trained and experienced; whether the equipment operated normally; whether the examinee's physical and mental state was suitable for testing; whether the environment was favorable without improper external interference; and whether standard pre- and post-test interview procedures were conducted. Consequently, polygraph reports in our country are widely questioned.
  Precisely for this reason, voluntarily taking a lie detector test is quite a risky decision. However, if one agrees to undergo the test, they must pay attention to the aforementioned requirements. If any requirement is not met, one must immediately object and demand corrections to ensure the test's accuracy and protect oneself. Of course, directly refusing the test at this point is also one of the coping methods.
  

Supplementary Legal status of lie detector test results

A lie detector test generates two things: one is the content spoken by the examinee, and the other is the physiological responses recorded by the polygraph equipment. Because different facets are focused upon, evaluations regarding the nature of a lie detector test will differ.

If the focus is placed on the "content stated by the examinee," the lie detector result will be viewed as possessing the nature of a testimonial statement. If a lie detector test is forced against the examinee's will, it may raise issues of infringing upon the right to silence or violating the privilege against self-incrimination. Conversely, if the focus of a lie detector test is placed on the "physiological responses recorded by the polygraph equipment" rather than the truthfulness of the examinee's answers, the nature of the test should be psychological assessment rather than a testimonial statement; in such cases, issues of infringing upon the right to silence or violating the privilege against self-incrimination do not arise.

This article posits that the focus of a lie detector test is not the truthfulness of the answers given by the examinee during the test, but rather their physiological responses during the test—meaning physiological responses serve as the baseline for determining deception, while whether the content of their statement is true is a separate matter. Therefore, the nature of a lie detector test should be psychological assessment rather than a testimonial statement.

Nevertheless, even if we place the focus of lie detector tests on "physiological responses," because tests record physiological responses through equipment while questions are answered, forcing a test against an examinee's will still infringes upon their inner freedom, thereby violating personal autonomy. Therefore, the examinee's "voluntary" and "genuine" consent must still be obtained before a lie detector test may be conducted. In other words, only test results obtained through a test conducted with the examinee's consent satisfy the prerequisite requirements for being admissible as evidence.

Related Provisions

• Article 161, Paragraph 1 of the Code of Criminal Procedure: "Prosecutors shall bear the burden of proof regarding the criminal facts of a defendant and shall indicate methods of proof."
  
• Article 9, Subparagraph 3 of the Detailed Operational Rules of the Criminal Investigation Bureau, National Police Agency, Ministry of the Interior: Matters handled by the Forensic Science Division include: "Forensics relating to firearms and ammunition, chemistry, trace evidence, documents, audio-video, lie detection, and behavioral science, etc."
  
• Article 3 of the Implementation Measures for Lie Detector Tests on Perpetrators of Sexual Assault Crimes Subject to Protective Supervision: "Lie detector tests as referred to in these Measures mean that personnel who have received professional and practical training in lie detection and possess professional knowledge and skills (hereinafter referred to as lie detector personnel) utilize polygraph equipment to record the physiological responses of examinees to read, analyze, and judge whether the examinee's statements are true."
  
• Article 6, Paragraph 1 of the Implementation Measures for Lie Detector Tests on Perpetrators of Sexual Assault Crimes Subject to Protective Supervision: "When conducting a lie detector test, the district prosecutors offices or local military prosecutors offices may have lie detector personnel within their agencies conduct it directly, or commission lie detector personnel or medical and relevant agencies possessing lie detector personnel to do so."
  
• Article 7 of the Implementation Measures for Lie Detector Tests on Perpetrators of Sexual Assault Crimes Subject to Protective Supervision: "When commissioning a lie detector test, the district prosecutors office or local military prosecutors office shall attach the following materials for reference by the lie detector personnel or lie detector agency (institution):
  1. The examinee's name, gender, date of birth, identity document serial number, place of residence, educational background, occupation, physical and mental condition, or other characteristics sufficient for identification.
  2. Protective supervision execution materials.
  3. Relevant assessment and treatment materials of the examinee.
  4. Other necessary reference materials."
  
• Article 8, Paragraph 2 of the Implementation Measures for Lie Detector Tests on Perpetrators of Sexual Assault Crimes Subject to Protective Supervision: "Lie detector personnel may exchange opinions with probation officers and personnel executing physical and mental treatment or counseling education before and after conducting a lie detector test, and shall pay equal attention to circumstances favorable and unfavorable to the examinee."
  
• Article 9 of the Implementation Measures for Lie Detector Tests on Perpetrators of Sexual Assault Crimes Subject to Protective Supervision: "When lie detector personnel, based on professional judgment, consider it inappropriate to conduct a lie detector test, they shall immediately notify the probation officer. The same shall apply when an examinee refuses to undergo a lie detector test."
  
• Article 10 of the Implementation Measures for Lie Detector Tests on Perpetrators of Sexual Assault Crimes Subject to Protective Supervision: "(Paragraph 1) After a lie detector test is completed, the lie detector personnel or lie detector agency (institution) shall prepare a lie detector report and reply by official letter to the originally commissioning district prosecutors office or local military prosecutors office.
  (Paragraph 2) The lie detector report shall state the time, location, technology used, results of the test, and information obtained during the implementation process, and shall attach the polygraph charts and the qualifications resume of the lie detector personnel.
  (Paragraph 3) Lie detector personnel or lie detector agencies (institutions) shall not leak secrets and personal data related to lie detector results known through their official duties.
  (Paragraph 4) Probation officers may, upon reporting and obtaining consent from prosecutors or military prosecutors, present lie detector results at community supervision and counseling network meetings for reference by sexual assault prevention centers, personnel executing physical and mental treatment or counseling education, or police agencies."