The Legal Standard
The legal standard that governs whether marriage to an American citizen or permanent resident renders you eligible for permanent residence in the U.S. is the "good faith" standard. Good faith requires only that you did not enter the marriage solely to obtain immigration benefits. In other words, the focus is on your intentions at the time of marriage, regardless of whether the marriage later ended in divorce.
Divorce While Your Application Is Pending
If your sponsoring spouse divorces you while your permanent residency petition is still pending, the issue is not immigration fraud but lack of a qualifying sponsor. You are obligated to inform immigration authorities of your divorce and your ex-spouse's sponsorship will be cancelled if U.S. immigration authorities learn of the divorce through any means. At this point, you will be asked to voluntarily depart the U.S. and may be deported if you refuse to comply. If you fail to notify immigration authorities of your divorce and they approve your permanent residence petition, they may revoke it at any time upon learning of the divorce and deport you, even years later.
Conditional Permanent Residents and Divorce
If your permanent residence petition was approved before your divorce -- even if the approval notice was still in the mail on the day you divorced -- you are less likely to be required to leave the U.S. If you were married less than two years on the date you were granted permanent residency, you are a "conditional permanent resident." Conditional permanent residency expires after two years unless you and your spouse file a joint petition to have the condition removed. Your spouse may file a joint petition with you even if you are already divorced at the time the petition is filed. If he refuses to assist you, you may apply for a waiver of the joint petition requirement based on either good faith marriage, extreme hardship or domestic abuse. Although you must notify immigration authorities of your divorce in your petition or waiver request, a divorce will disqualify you from having your condition removed only if immigration authorities conclude you violated the "good faith" standard.
Unconditional Permanent Residents and Divorce
If you were married for two or more years when your permanent residence was approved, or your condition was removed after two years, you are an unconditional permanent resident. If your spouse divorced you after you become an unconditional permanent resident, you are not required to notify immigration authorities of your divorce and no further petitions or interviews are required unless you seek U.S. citizenship. Even if immigration authorities learn of your divorce, they will take action against you only if they conclude your divorce evidences your marriage was never entered into in good faith in the first place. Filing for divorce the day after you receive your permanent residence card, for example, may raise questions about your original intentions.