A dying declaration is a statement made by a person as to the cause of his death, or as to any of the circumstances of the transaction which resulted in his death, in cases where the cause of that person's death comes into question. It is an exception to the general rule of hearsay evidence, which ordinarily excludes statements made by a person who is not produced as a witness in court. The legal basis for its admissibility in India is Section 32(1) of the Indian Evidence Act, 1872. The rationale behind accepting such a statement is the legal maxim 'Nemo moriturus praesumitur mentiri,' meaning 'a man will not meet his maker with a lie in his mouth' – the belief that a person on the verge of death would not lie.

Evidentiary Value: Dying declarations are considered a strong piece of evidence and are admissible in both civil and criminal cases. Their evidentiary value is significant because they are often the only direct evidence available regarding the circumstances of the death. However, their value is not absolute and is subject to careful scrutiny by the court. Factors influencing its weight include:

1. Mental and Physical Condition: The declarant must have been in a fit state of mind to make the statement and understand its implications.
2. Consistency: If there are multiple dying declarations, their consistency is crucial. Inconsistencies can reduce their reliability.
3. Corroboration: While not legally mandatory, corroboration by other evidence can significantly enhance the credibility of a dying declaration, especially if there are doubts about its veracity.
4. Voluntariness: The declaration must be voluntary and not a result of tutoring, prompting, or coercion.
5. Completeness: A complete statement is generally given more weight than an incomplete one.
6. Recording: The manner in which it is recorded (e.g., by a Magistrate, doctor, or police officer) can affect its weight. A declaration recorded by a Magistrate, after ensuring the declarant's fitness, is generally considered highly reliable.

Conviction Solely on Dying Declaration: Yes, an accused can be convicted solely on the basis of a dying declaration, provided the court is fully satisfied that the dying declaration is truthful, voluntary, reliable, and inspires full confidence. The Supreme Court of India has consistently held that there is no absolute rule of law requiring corroboration of a dying declaration. If the court is convinced that the dying declaration is free from any infirmity and is a true account of the incident, it can form the sole basis for conviction.

However, the courts adopt a rule of prudence and caution. They meticulously examine the dying declaration for any suspicious circumstances, inconsistencies, or possibilities of tutoring. If there are any doubts regarding its genuineness or if it appears to be inconsistent with other evidence, the court may look for corroboration. But if, after careful scrutiny, the court finds the dying declaration to be wholly reliable and trustworthy, it can indeed be the sole foundation for a conviction.