That the words 'conclusive proof' in Section 112 preclude any evidence in rebuttal except in the solitary situation provided in the very Section is clear from the decision of the Supreme Court in Venkateswarlu v. Venkatanarayana, AIR 1954 SC 176. There, a suit was filed by a Hindu son against his father for partition and it was contended for the father that the plaintiff was not his legitimate son. The defendant relied upon certain documents by which he had agreed to pay maintenance to the plaintiff's mother and upon a deed gifting a house to her and also relied on assertions made in a previous suit that he had no intercourse with her after he married a second wife. The said contention was rejected. It was held that though the plaintiff's mother lived in the house gifted to her there was no 'impossiblity' of cohabitation. In that case, B.K. Mukherjee, J. (as he then was) observed :
"It may be stated at the outset that the presumption, which Section 112 of the Indian Evidence Act contemplates, is a conclusive presumption of law which can be displaced only by proof of the particular fact mentioned in the section, namely, non-access between the parties to the marriage, at any time when according to the ordinary course of nature, the husband could have been the father of the child. Access and non-access again connote, as has been held by the Privy Council : vide Karpaya v. Mayandi, AIR 1934 PC 49, existence and non-existence of opportunities for marital intercourse ...........proof of non-accesss must be clear and satisfactory."
Therefore, the presumption raised in Section 112 is conclusive and rebuttal evidence can be permitted to prove that the child is not legitimate, in the only one situation provided in Section 112 and not in any other situation.
Supreme Court had a brief overview of authorities regarding section 112 from para 10 - 22 :
Shyam Lal @ Kuldeep vs Sanjeev Kumar & Ors on 15 April, 2009
"10. Section 112 of the Indian Evidence Act is based on English law. Section 112 reproduces rule of English law that it is undesirable to inquire into paternity of child when mother is married woman and husband had access to her. Adultery on her part will not justify finding of illegitimacy if husband has had access. [See: Nga Tun E v. Mi Chon A.I.R. 1914 Upper Burma 36].
11. More than a century ago in Bhima v. Dhulappa (1904) 7 Bombay Law Reports 95, the Court aptly observed that section 112 of the Evidence Act is based on the principle that when a particular relationship, such as marriage, is shown to exist, then its continuance must prima facie be preserved.
12. The fact that a woman is living in notorious adultery, though of course it amounts to very strong evidence, is not, in itself quite sufficient to repel this presumption [See: R v. Mansfield, 1941, 1 QB 444, 450].
13. In 1947 All LJ 569 at page 572 Hardan Singh v. Mukhtar Singh & Anr. , the Allahabad High Court observed:
"The mere fact that a woman is immoral or is living in a house separate from that of her husband is having relations with other men is not sufficient to rebut the conclusive presumption of legitimacy which is raised by section 112 of the Evidence Act, unless it is proved that the husband and wife had no access to each other during the period indicated in the section."
14. In Lal Haribansha v. Nikunja Behari, ILR 1960 Cuttack 230, relying on Ma Wun Di and Another v. Ma Kin and Others XXXV IA 41, the Court stated that:
"It is the principle of law that "Odiosa et inkonesta non sunt in lege prae sumenda" (Nothing odious or dishonourable will be presumed by the law). So the law presumes against vice and immorality. One of the strongest illustrations of the principle, is the presumption in favour of legitimacy of children in a civilized society. But, where illegitimacy seems as common as marriage and legitimacy, a presumption of legitimacy cannot be drawn and legitimacy or illegitimacy will have to be proved like any other fact in issue."
15. The High Court placed reliance on a judgment of this court in Chilukuri Venkateswarlu v. Chilukuri Venkatanarayana AIR 1954 SC 1761 as under:-
"It may be stated at the outset that the presumption which section 112 of the Indian Evidence Act contemplates is a conclusive presumption of law which can be displaced only by proof of the particular fact mentioned in the section, namely, non-access between the parties to the marriage at a time when according to the ordinary course of nature the husband could have been the father of the child. Access and non-access again connote, as has been held by the Privy Council (Vide Karapaya v. Mayandy, AIR 1934 PC 49(A), existence and non- existence of opportunities for material intercourse. It is conceded by Mr. Somayya,