An annulment is marriage that was never valid

The legal effect of an annulment is to void the marriage as though it never existed. Some of the reasons for granting an annulment are.

The consent to marriage of one of the parties was obtained by fraud and the parties have not cohabitated (lived together as husband and wife) after learning of the fraud. These circumstances are very fact specific.

Generally, fraud by a party to the marriage is grounds for an annulment.

Cases where annulments have been granted in the past based on fraud include the following circumstances.
 
One person married another solely to obtain a green card, or citizenship; Eg: In Poupart v. District Court of 7th Judicial District, et al, 34 Nev. 336, 123 P. 769 (1912), fraud by a party to the marriage was held grounds for an annulment.

One person misrepresented or concealed that he/she would not fulfill a prenuptial promise to become a U.S. citizen.

One person misrepresented a willingness to consummate the marriage and reside together following the marriage.
 
One person misrepresented a willingness to conceive children following the marriage.
 
One person misrepresented or concealed that he/she would not engage in sexual intercourse following the marriage. 

One person misrepresented or concealed impotency and/or the inability to engage in sexual relations with the other spouse.
 
One person represented to the other party that he/she was willing and able to conceive children during the marriage, when that person was actually known to be sterile and unable to conceive children.
 
The wife misrepresented or concealed that she was pregnant by another man at the time of marriage.

Prior to the marriage the wife claimed to be pregnant, but it was disclosed after the marriage that she was not pregnant.

One person misrepresented or concealed that he/she was homosexual.
 
One person misrepresented or concealed that he/she had physically abused a prior person in their lives (Nevada court only).
 
One person misrepresented or concealed that he/she had a criminal history.
 
One of the parties was forced into the marriage because of duress, threats and intimidation and would not have entered into the marriage except for the other party’s conduct.
 
One person misrepresented or concealed that he/she was not in good health or had a disease.
 
One person misrepresented or concealed that he/she suffered from a mental illness or had been institutionalized in a mental hospital.
 
One person misrepresented or concealed that he/she suffered from alcohol or drug addiction.

One person misrepresented or concealed that he/she suffered from a gambling addiction.
 
One person misrepresented or concealed that he/she married the other person solely to secure access to that parties' money, wealth or property.
 
One person misrepresented or concealed that he/she would not fulfill the terms of a prenuptial agreement to reimburse the other party for alimony lost due to this marriage.
 
One person misrepresented or concealed that he/she would not fulfill a prenuptial promise to have a religious marriage ceremony performed after the civil marriage ceremony.

One person misrepresented or concealed his/her present religious conviction.

One person misrepresented or concealed his/her intention to embrace the other parties religion.
 
One person misrepresented or concealed his/her prior divorce and the other party is a Roman Catholic.
One person misrepresented or concealed his/her anti-Semitic feelings.
One person misrepresented or concealed that he/she was a practicing Orthodox Jew.

Relevant legal forms include:

Motion to declare marriage void ab initio and Judgment of Annulment
Decree of Annulment
Cover Sheet - Annulment
Petition for Annulment
Decree of Annulment
Record of Divorce or Annulment
Permissible Form for Orders of Publication - Divorce or Annulment
Certificate of Absolute Divorce or Annulment
Complaint For Annulment
Summons - Annulment