Modern Hindu law under statutory law and judicial precedent envisions multiple theories, namely:

1. Fault theory
2. Prevailing circumstances
3. Mutual Consent
4. Irretrievable breakdown theory

Among them all, Fault theory is a ground for granting Divorce based on the guilty conduct of one parties, which makes it unfeasible for the other party to stay in the relationship. Thus, Divorce is granted as a relief to the Innocent party of the relationship. Adultery is one type of Fault theory that finds its place in Hindu law, provided in Section 13(1)(i) of the Hindu Marriage act of 1955.

It must be however be noted that the section doesn't use the word "Adultery" per se, nonetheless impliedly provides the definition of the term as "after the solemnization of the marriage, had voluntary sexual intercourse with any person other than his or her spouse".

Before its amendment in 1976, the Hindu Marriage Act stipulated that a spouse was entitled to as divorce if the other spouse was, according to Section 13(i), "living in adultery"; that is, there was a continuous adulterous relationship ongoing. Now, however, after the amendment, even a single lapse in the matrimonial sanctity would be enough to furnish ample ground for a decree of divorce.

This phrase "Living in adultery" has been retained in its form in section 125(4) of The Code of Criminal Procedure, 1973, where it has been used as a bar to the wife for claiming an allowance for maintenance. The authors of Mulla Hindu law recommended that the section was in need of amendment as it had remained static in front of other legislation.1 Alas, in the New Bhartiya Nagrik Suraksha Sanhita of 2023, section 125 of CrPC has been retained almost completely in the new section 144, and still in section 144(4), maintenance can only be denied if the wife was "living in adultery".

Direct evidence of Adultery is not a requirement to prove the offense of adultery because it would be unreasonable to expect such a piece of evidence. Adequate circumstantial evidence that leads to a justified conclusion of adultery is generally as a rule accepted as good proof of the offense.

In the English case of Raspin v. Raspin 2, popularly known as Hotel bill and register case, evidence from the hotel register showed the respondent being in a hotel bedroom with another woman. The view was expressed that the court would insist on the evidence of the background of an adulterous Association.

The mere opportunity of committing adultery can on its own be used as proof, but when the proof of strong disposition is added on top of it, then it's strong proof.

In the case of Dipawanta Roy v Ronobroto Roy 3 it has been held, that it would be permissible for the court to direct blood tests in order to prove adultery, though it should be avoided if and whenever possible as it threatens to put the paternity of the child in threat. If the Wife chooses to disregard the order directing the test, an adverse presumption can be drawn against her as contemplated in section 114 of the evidence act (now the new section 119 of The Bharatiya Sakshya Adhiniyam, 2023).

However, this doesn't mean that a conclusion can be reached in a casual manner. While direct evidence isn't required, circumstantial evidence is required to be justified, and there must be a high probability of the happening of the offense.

According to Shanta Bai v. Ram Bilash, the allegation of adultery on a woman is a serious thing, and thus dissolving marriage on its ground requires close scrutiny of the evidence.

Once the adulterous relationship has been proved to the satisfaction of the court, a petition of divorce would be due in the favour of the innocent party.

As discussed above, in the case when the party at fault was the wife, and in case she is "living in adultery", that is she is part of a continuous adulterous association, then the husband would not be bound to provide her with the allowance of maintenance under section 125 of The Code of Criminal Procedure (Now the section 144 of The Bharatiya Nagarik Suraksha Sanhita, 2023).

It must be noted, that earlier adultery was a criminal offense under section 497 of the Indian Penal Code of 1860. Adultery however was decriminalized, and section 497 was struck down by the Supreme Court in the landmark case of Joseph shine v. Union of India4 on grounds of violation of Articles 14, 15 and 21 of the Indian Constitution because it compromised with the dignity of women.

To conclude, Adultery, or having voluntary sexual intercourse with someone other than your spouse is a ground for divorce according to The Hindu Marriage Act, 1955, and a decree can be sought by the innocent party under section 13(1)(i) of the aforementioned act. The party need not give direct evidence, but circumstantial evidences are enough if they can prove that inference of Adultery was highly probable.

Marriage in Hindu law is considered a sacrament and carries with it not only martial obligations but spiritual also. In case when the sanctity of such a union is destroyed by the fault of one party, it would be just that remedy be provided by way of divorce. Better is it that such a marriage be dissolved by the court, than have an innocent party sacrifice their matrimonial life in a suffocating and untrustworthy Union.

Notes:

1. Mulla's Principles of Hindu Law 23rd edition. s13.11
2. (1953) 2 All ER 349
3. AIR 2015 SC 418
4. AIR 2018 SUPREME COURT 4898