(A) All the marriages completed before or after the commencement of the Act can be considered invalid on the following grounds - 

1) Impotency of the partners

2) Violation of the condition mentioned in Section 5(ii) - Partner is suffering from a serious mental disorder

3) Consent of partner by force or fraud

4)  During the marriage, the partner is pregnant by another person during the time of marriage. 

(B) Despite the different conditions mentioned in the part (A) - 

(1) On the ground of the clause (d) of the sub-section (1) shall be contemplated unless the court is satisfied-

(i) If the petitioner was unaware of the facts alleged at the time of marriage,

(ii) If after the discovery of the said ground of void marriage there was no sexual intercourse among them.