I. Under the Hindu Marriage Act, 1955
A. Void Marriages (Section 11):

A marriage is void ab initio if:

Bigamy: Either party has a living spouse at the time of the marriage.
Prohibited Relationship: The parties are within the degrees of prohibited relationship (unless permitted by custom).
Sapinda Relationship: Marriage between sapindas is invalid (unless custom allows it).
B. Voidable Marriages (Section 12):

A marriage is valid until annulled by court on the following grounds:

Impotency: Either party is incapable of consummating the marriage.
Mental Disorder: Either party is of unsound mind or suffers from mental illness rendering them unfit for marriage and procreation.
Consent Obtained by Force or Fraud: If consent was obtained through coercion, misrepresentation, or concealment of material facts.
Pregnancy by Another Man: The bride was pregnant by another person at the time of marriage, without the groom’s knowledge.
II. Under the Special Marriage Act, 1954
The grounds are largely similar to the Hindu Marriage Act.
Additional focus is on valid consent, mental capacity, and absence of disqualifying relationships.
III. Under Christian and Muslim Law
Christian Marriage Act: Grounds include fraud, impotency, and mental incapacity.
Muslim Law: Marriage (nikah) can be void, irregular (fasid), or valid depending on compliance with Islamic requirements like consent, age, and relationship.
Conclusion:
Nullity of marriage ensures protection against invalid or coerced marital relationships. Indian law recognizes that marriages lacking valid consent, legal capacity, or compliance with social norms can be annulled to uphold the dignity and rights of individuals.

In Indian law, nullity of marriage means declaring a marriage void or voidable, i.e., legally invalid from the beginning or cancelable under certain conditions. The grounds vary slightly under different personal laws, but here are the common grounds:

Grounds for Void Marriages (Marriage is treated as never having taken place):
1. Bigamy – Either party was already married at the time (Section 5(i), Hindu Marriage Act).
2. Prohibited Degree of Relationship – Parties are related too closely (unless custom permits).
3. Sapinda Relationship – Marriage within certain blood relations is not allowed.
4. Lack of Valid Ceremony – If essential marriage rites were not followed.


Grounds for Voidable Marriages (Marriage is valid until annulled by a court):
1. Impotency – If one party is unable to consummate the marriage (Section 12(1)(a), Hindu Marriage Act).
2. Unsoundness of Mind – At the time of marriage, a party was mentally unfit to consent.
3. Fraud or Misrepresentation – Consent was obtained by deception or concealment of facts (e.g., about age, disease, religion).
4. Force or Coercion – Marriage was not entered into with free will.
5. Pregnancy by Another Person – The wife was pregnant by another man at the time of marriage (not known to the husband).