When there is a question whether an act was accidental or intentional, or done with a particular knowledge or intention, the fact that such act formed part of a series of similar occurrences, in each of which the person doing the act was concerned, is relevant.
Illustrations
(a) A is accused of burning down his house in order to obtain money for which it is insured. The facts that A lived in several houses successively each of which he insured, in each of which a fire occurred, and after each of which fires A received payment from a different insurance company, are relevant, as tending to show that the fires were not accidental.
(b) A is employed to receive money from the debtors of B. It is A's duty to make entries in a book showing the amounts received by him. He makes an entry showing that on a particular occasion he received less than he really did receive. The question is, whether this false entry was accidental or intentional. The facts that other entries made by A in the same book are false, and that the false entry is in each case in favour of A, are relevant.
(c) A is accused of fraudulently delivering to B a counterfeit currency. The question is, whether the delivery of the currency was accidental. The facts that, soon before or soon after the delivery to B, A delivered counterfeit currency to C, D and E are relevant, as showing that the delivery to B was not accidental.
Legal Commentary & Landmark Judgments: Section 13
Section 13 codifies the 'doctrine of system', permitting evidence of a series of similar occurrences to disprove accident or mistake and establish intentional design or guilty knowledge.
The recurrence of identical, advantageous transactions negates the probability of accident, establishing an underlying deliberate pattern.
The application of this section is subject to strict judicial limits: similar fact evidence cannot be introduced to prove the physical commission of the act itself (the actus reus). It is admissible only after the physical act has been independently established by credible evidence, whereupon the similar occurrences are considered solely to determine whether the act was executed with criminal intent or guilty knowledge.
Section 13 is a decisive investigative and prosecutorial tool in financial fraud, cyber-scams, and insurance arson trials. When an accused claims an erroneous bank transfer or unauthorized access was an isolated technical glitch, prosecutors can introduce evidence of repeated similar transactions across accounts to establish coordinated, intentional criminality.