Polygraph test is famously known as the lie detector test which is used by the law enforcing agencies to find the culprit. It involves noticing the change in a person’s blood pressure and heartbeat in order to figure out whether the statement made by him is true or false. Narco Analysis Test on the other hand serves the same purpose but the method used here is different. It involves administration of a drug under the influence of which the person answers the statements truthfully. With the evolution of science and technology these scientific tests have also been innovated in order to help serve justice better. The use of these tests by the law enforcing agencies sparked a debate across the world relating to the validity of these tests. There were proponents for these tests who argued that these eased the process of finding the truth and helped in putting accused behind the bars. The opponents of these tests argued that these tests were a violation of the Constitution and the principle of self-incrimination. They also argued that these tests were not reliable and also has the possibility of giving false results in few cases. These tests also did not take into consideration other factors like fear, stress and coercion or duress into account. Under any of these circumstances the person’s blood pressure or heart rate could increase, even if he was not lying. Hence, they argued that these tests should not be admissible as evidence in order to sentence a person. This paper tries to critically analyse the process used in these tests and showcase why they should not be used under the Indian laws to trace the accused person. It mainly highlights how these tests violate the Indian Constitution and hence should be rendered invalid in India.