Nullity of marriage is considered when -

Ref:The essential of forensic medicine and toxicology Dr.K.S NARAYAN REDDY 32nd edition pg no 371 Nullity of marriage (S.12 Hindhu marriage Act) that is marriage never to have existed in law. A marriage can be nullified 1. when either pay was under the age of marriage contract 2. when one pay was of unsound mind or a mental defective at the time of marriage 3.when one person was already validly married 4. where the marriage has not been consummated due to impotence or wilful refusal 5.where the woman was pregnant by another man at the time of marriage