Polygraph Test: In the Kolkata Rape-Murder Case

Recently, the Central Bureau of Investigation (CBI) conducted a polygraph test on the main suspect in the Kolkata doctor rape-murder case. This test aims to evaluate the credibility of the suspect during the investigation.

About Polygraph Test:

A polygraph test, or lie detector test, is designed to measure physiological changes that are thought to occur when a person is being deceptive. Here’s a more detailed look at how it works and its various aspects:

How It Works:

1. Preparation: The subject is connected to the polygraph machine via sensors placed on the body. Common placements include:
   1. Heart rate: A cuff or sensor around the chest.
   2. Blood pressure: A cuff on the upper arm.
   3. Respiration: Belts around the chest and abdomen.
   4. Galvanic Skin Response (GSR): Electrodes attached to the fingers or palms.
2. Questioning: The examiner asks a series of questions. These can include control questions (which are known to be true or false) and relevant questions related to the issue at hand.
3. Data Collection: The polygraph records the physiological responses while the subject answers the questions. The machine tracks changes in heart rate, blood pressure, respiration, and skin conductivity.
4. Analysis: The examiner analyzes the physiological data to look for significant changes in response to specific questions. The theory is that deceptive responses will cause physiological changes due to stress or anxiety.

Types of Questions:

1. Relevant Questions: Directly related to the matter being investigated.
2. Control Questions: Used for comparison, often about unrelated matters or minor transgressions.
3. Irrelevant Questions: Neutral questions that do not pertain to the investigation, used to establish a baseline.

Accuracy and Reliability:

1. Accuracy: Polygraph tests are not infallible. They can produce false positives (indicating deception when the person is truthful) and false negatives (failing to detect deception when it occurs). Factors like nervousness, medical conditions, and individual differences can affect results.
2. Scientific Debate: The scientific community remains divided on the reliability of polygraphs. Critics argue that physiological responses are not a definitive indicator of deception, while proponents believe they can be useful in conjunction with other investigative tools.

Legal and Practical Use:

1. Admissibility in Court: The use of polygraph results in court varies by jurisdiction. Some courts accept them as evidence under specific conditions, while others do not.
2. Employment and Investigations: Polygraphs are sometimes used in pre-employment screenings, criminal investigations, and security clearances. However, their results are typically used as a supplementary tool rather than definitive proof.

Ethical and Psychological Considerations:

1. Privacy Concerns: The use of polygraphs raises privacy issues, as the process involves sensitive physiological data.
2. Stress Impact: The experience of taking a polygraph can be stressful, potentially affecting the results..

Supreme Court Judgements:

1. Consent Requirement: According to the Supreme Court ruling in Selvi & Ors vs State of Karnataka & Anr (2010), polygraph tests can only be conducted with the accused's informed consent.
2. Informed Consent: The accused must receive a thorough explanation of the test's physical, emotional, and legal implications and have access to legal counsel.
3. Guidelines Adherence: The National Human Rights Commission’s 2000 guidelines for polygraph tests must be followed.
4. Documentation: Consent must be documented before a judicial magistrate.
5. Admissibility: Information obtained through a consensual polygraph test may be admitted in court.

What is a Narco Test?

A narco analysis test involves injecting sodium pentothal into the accused, inducing a hypnotic or sedated state to reduce their ability to fabricate responses, thus aiming to reveal truthful information.

Differences between Polygraph tests and Narco analysis tests: 1. Methodology: Polygraph Test: Technology: Uses a device that measures physiological responses such as heart rate, blood pressure, respiratory rate, and skin conductivity. Procedure: During the test, the subject is asked a series of questions. The polygraph records physiological changes that may occur in response to these questions, which are then analyzed to detect signs of deception. Narco Analysis Test: Technology: Involves administering a drug, typically a form of sodium pentothal or similar, to induce a state of heightened suggestibility or reduced inhibition. Procedure: The subject is given the drug intravenously, which purportedly makes them more likely to speak freely or reveal information. The subject is then interviewed while under the influence of the drug. 2. Accuracy and Reliability: Polygraph Test: Accuracy: The accuracy of polygraph tests is controversial. Critics argue that physiological responses measured by polygraphs are not always reliable indicators of deception and can be influenced by various factors such as anxiety or nervousness. Reliability: The test's reliability is debated within the scientific community. Some studies suggest it has a high false-positive rate, while others argue it has some validity when used properly. Narcoanalysis Test: Accuracy: The reliability of narcoanalysis is also debated. The effectiveness of the drug in eliciting truthful responses is questioned, as subjects might still be capable of lying or withholding information. Reliability: The test is controversial and considered less reliable because the induced state may not always lead to accurate or truthful information. The results can be influenced by the subject’s awareness and the skill of the interviewer. 3. Legal and Ethical Considerations: Polygraph Test: Legal Status: Polygraph results are generally not admissible as evidence in many courts because of concerns about their reliability. However, they are often used in investigations and pre-employment screenings. Ethical Issues: Ethical concerns include the potential for coercion and the implications of false positives. There's also debate about the privacy implications of monitoring physiological responses. Narcoanalysis Test: Legal Status: Narcoanalysis is controversial and often considered inadmissible in court as evidence due to concerns about its reliability and the potential for coerced confessions. Its use varies widely by jurisdiction. Ethical Issues: There are significant ethical concerns regarding the use of drugs to extract information, including issues of consent and the potential for psychological harm. The voluntary nature of the subject's participation can be questioned, and the effectiveness of the method is debated. 4. Application and Use: Polygraph Test: Application: Used primarily in criminal investigations, pre-employment screenings, and security clearances. It can be employed to assess the truthfulness of statements or to verify alibis. Use: Typically used in non-invasive settings where monitoring physiological responses is feasible. Narcoanalysis Test: Application: Often used in criminal investigations, particularly in cases where the subject may have information that they are reluctant to divulge. Use: Requires medical supervision due to the administration of drugs and the potential side effects or risks associated with the procedure.

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