An annulment means a judge will rule that a marriage was not valid because of a defect that existed when the parties were married.  A divorce means a judge will terminate a marriage for reasons that occurred after the marriage took place.

Common reasons for an annulment are: bigamy, fraud, duress, sterility or impotency and other grounds:

1. Bigamy.  A marriage is illegal if it is performed while a prior spouse, from whom no divorce was ever granted, is still living.  If husband is married to a living spouse (spouse #1) and then husband marries a new spouse (spouse #2) without first getting divorced from spouse #1, the marriage to spouse #2 is deemed to have never taken place.

2. Fraud and Duress.  In order to get married, both parties have to freely and voluntarily enter into the marriage — the contractual relationship.  If a spouse would not have entered into a marriage except for fraud or duress, the voluntary consent necessary for a valid marriage (a valid contract) does not exist.  If a future spouse makes false and material representations to another future spouse, an annulment is possible.  

3. Sterility or Impotency.  An annulment is possible if one spouse is incapable of having children, this incapacity existed at the time of the marriage, the physical incapacity is incurable and the other spouse does not know about the incapacity on or before the  marriage ceremony.  

4. Other grounds.  There can be other grounds to justify an annulment — it just depends on your particular situation.  Some examples are:
a. One spouse has a venereal disease and does not tell his or her spouse;
b. One spouse will not have sex with his or her spouse;
c. A spouse is deemed to have been mentally incompetent at the time of the marriage ceremony;
d. A spouse is under age;
e. A marriage between parties who are related within certain degrees of consanguinity or affinity.  Consanguinity refers to a blood relationship and affinity refers to the relationship between one spouse and a blood relative of the other spouse; and
f. A marriage between persons of the same sex.