The Supreme Court explained the concept in its decision in Sharda v. State of Rajasthan in the following terms;
32. In the case in hand, the conviction of the appellant is based on the last dying declaration Exh.P- 18, said to have been recorded in presence of Executive Magistrate. The principle on which dying declarations are admitted in evidence is indicated in legal maxim:
“Nemo moriturus proesumitur mentiri – a man will not meet his Maker with a lie in his mouth.”
33. It is indicative of the fact that a man who is on a death bed would not tell a lie to falsely implicate an innocent person. This is the reason in law to accept the veracity of her statement. It is for this reason, the requirements of oath and cross-examination are dispensed with. Besides, if the dying declaration is to be completely excluded in a given case, it may even amount to miscarriage of justice as the victim alone being the eye-witness in a serious crime, the exclusion of the statement would leave the court without a scrap of evidence.
34. Though a dying declaration is entitled and is still recognized by law to be given greater weightage but it has also to be kept in mind that accused had no chance of cross-examination. Such a right of cross-examination is essential for eliciting the truth as an obligation of oath. This is the reason, generally, the court insists that the dying declaration should be such which inspires full confidence of the court of its correctness. The court has to be on guard that such statement of deceased was not as a result of either tutoring, prompting or product of imagination. The court must be further satisfied that deceased was in a fit state of mind after a clear opportunity to observe and identify the assailants. Once the court is satisfied that the aforesaid requirement and also to the fact that declaration was true and voluntary, undoubtedly, it can base its conviction without any further corroboration. It is not an absolute rule of law that the dying declaration cannot form the sole basis of conviction unless it is corroborated. The rule requiring corroboration is merely a rule of prudence.