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Narco Analysis Tests – Importance, Procedure, Law in India

Narco Test Procedure


What is a Narco Test?

Narco analysis tests involve the injection of sodium pentothal, which is also called Truth Serum. The administration of the drug (sodium pentothal) lowers an individual’s self-consciousness, thereby allowing him/her to speak freely. This happens when the person becomes less inhibited and enters a hypnotic state. This stage allows examiners to question the subject and get real answers.

Narco test is done under the observation of a psychologist, investigating officer, or forensic expert. It is a lighter alternative to other commonly known third-degree treatments used by investigating departments.”

Procedure: How is the test performed?

Before the actual procedure, the subject is physically diagnosed to check whether his/her medical condition is worth the test.

The individual is injected with hypnotics Sodium Pentothal, also known as Thiopentone. However, the dosage is dependent on the individual’s age, sex, and other medical conditions. The wrong dosage can result in an individual’s death or maybe coma. In addition to this, other precautions need to be taken while conducting the test.

The application of the drug sedates the patient and puts them to sleep.

Once the drug is injected, the individual is put in a state where he/she can answer only specific questions. Such tests are not always permittable in the law courts because when the person is in a semi-conscious state, they are not prepared to answer most of the questions. On the other hand, other courts accept it fully.

P300 Tests: What are these?

When the brain identifies the person’s sound, it produces a particular type of electric wave, which is called P300. During the test, the person is seated in front of the monitor. He further showed some images or made to hear different sound types. Post which the sensors attached to the patient’s brain start monitoring electrical activity in the brain and record as P300 waves. The P300 electric wave is generated only if the person carries any link with the stimulus- which is pictures or sounds (in this test).

Investigators conduct P300 tests to evaluate their findings and conclude whether a suspect is speaking the truth. This test is also known as the Brain Mapping Test.

Narco Test Importance, Law in India

How is it different from the Polygraph test?

A polygraph test, which is popular as a lie detector test, uses an instrument that evaluates and records several physiological indicators, like breathing rhythms, blood pressure, skin problems, respiration, pulse, etc. This happens when the suspect goes through a series of interrogations.

A polygraph test is based on the assumption that there is a link between the mind and body. Various components of a polygraph machine conduct it. Devices like sensitive electrodes or cardio cuffs are attached to the person, and variables like blood pressure, respiration, change in sweat gland, blood flow, etc., is measured.

A number is assigned to each recorded answer to understand whether the person is lying, telling the truth, or is uncertain.


Are Narco tests allowed by Indian Court?

  • In 2010 ‘Selvi & Ors vs State of Karnataka & Anr’, the Supreme Court ruled that no lie detector or polygraph tests should be conducted “except on the agreement of the accused”.
  • Those who still wish to must have legal, emotional, or physical implications of the test – the court stated further.
  • The subject’s permission should be recorded and presented to the magistrate.

The court analyzed the scope of Article 20 (3), which describes that an accused should never be forced to be a witness against himself.

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