Sardul Singh v. State of Bombay [1957 SC]

It is recognised on well established authority that the principle underlining the reception of evidence of the statements, acts and writings of one co-conspirator as against the other is on the theory of agency. Ordinarily, a person cannot be made responsible for the acts of others unless they have been instigated by him or done with his knowledge or consent. This section provides an exception to that rule, by laying down that an overt act committed by any one of the conspirators is sufficient, (on the general principles of agency) to make it the act of all.

But then, the opening of words of the Section makes it abundantly clear that such concept of agency can be availed of, only after the Court is satisfied that there is reasonable ground to believe that they have conspired to commit an offence or an actionable wrong. In other words, only when such a reasonable ground exists, anything said, done or written by any one of them in reference to their common intention thereafter is relevant against the others, not only for the propose of proving the existence of the conspiracy but also for proving that the other person was a party to it.