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Narco and Polygraph Test

Narco Test and Polygraph Test

About Narco Test and Polygraph Test

The Narco test is also known as the narcoanalysis test. During the test, sodium pentothal is injected into the person’s body. Also known as the ‘truth serum’, this injection transports the accused to a hypnotic state.

In this state, it is believed, the accused is incapable of lying. But in India, the Narco analysis report is not admissible as primary evidence in the court.

A polygraph test is another form of physiological examination, but in this test, no substances are injected into the person’s body. Instead, instruments to measure blood pressure, pulse rate, breathing, sweat glands and blood flow is attached to the person. After this, he/she would have to answer some questions.

A numerical value is assigned to each response to calculate if the person is lying or telling the truth.


The term narco-analysis is derived from the Greek word narko (meaning anaesthesia or Torpor). It is used to describe a diagnostic and psychotherapeutic technique that uses psychotropic drugs, particularly barbiturates.

What is the constitutionality in India?

In 2010, a Supreme Court ruling said that the use of narco analysis, brain mapping and polygraph tests on the accused, suspected and witnesses to a crime, without their consent, was unconstitutional and violated their right against self-incrimination.

It also said the ‘Guidelines for the Administration of Polygraph Test on an Accused’ published by the National Human Rights Commission in 2000, must be strictly followed.

The court took into consideration international norms on human rights, the right to a fair trial, and the right against self-incrimination under Article 20(3) of the Constitution.

These rulings were given in the case of Selvi & Ors vs State of Karnataka & Anr (2010).

The present situation of Narco test and Polygraph Test is unconstitutional and not a valid as a evidence. If the consent was not taken by accuse.

It also said that such test results could not be admitted in evidence; however any information/material subsequently discovered with the help of tests undertaken voluntarily could be admitted.

Despite the ruling however, these tests continue to be used, to date.

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