Section 9 of Evidence Act "Facts necessary to explain or introduce relevant facts"
Facts necessary to explain or introduce a fact in issue or relevant fact, or which support or rebut an inference suggested by a fact in issue or relevant fact, or which establish the identity of any thing or person whose identity is relevant, or fix the time or place at which any fact issue or relevant fact happened, or which show the relation of parties by whom any such fact was transacted, are relevant in so far as they are necessary for that purpose
(a) The question is, whether a given document is the will of A.
The state of A?s property and of his family at the date of the alleged will may be relevant facts.
(b) A sues B for a libel imputing disgraceful conduct to A; B affirms that the matter alleged to be libelous is true.
The position and relations of the parties at the time when the libel was published may be relevant facts as introductory to the facts in issue.
The particulars of a dispute between A and B about a matter unconnected with the alleged libel are irrelevant though the fact that there was a dispute may be relevant it is affected the relations between A and B.
(c) A is accused of a crime.
The fact that, soon after the commission of the crime, A absconded from his house, is relevant, under section 8 as conduct subsequent to and affected by facts in issue.
The fact that at the time when he left home he had sudden and urgent business at the place to which he went is relevant, as tending to explain the fact that he left home suddenly.
The details of the business on which he left are not relevant, except in so far as they are necessary to show that the business was sudden and urgent.
(d) A sues B for inducing C to break a contract of service made by him with A.C,on leaving A?s service, says to A?"I am leaving you because B has made me a better offer" . This statement is a relevant fact as explanatory of Co?s conduct, which is relevant as a fact in issue.
(e) A accused of theft, is seen to give the stolen property to B, who is seen to give it to A?s wife. B says as he delivers it?"A says your are to hide this". B?s statement is relevant as explanatory of a fact which is part of the transaction.
(f) A is tried for a riot and is proved to have marched at the head of a mob. The cries of the mob are relevant as explanatory of the nature of the transaction.