Hardship Waivers: Any undocumented immigrant who leaves the United States after being here unlawfully for more than 180 days is barred from returning for three years. The bar is ten years for anyone unlawfully present here for one year or more.
However the law provides for a waiver, ie the bar does not apply if the visa applicant can prove that a US citizen or permanent resident spouse or parent will suffer extreme hardship if the family is separated. The waiver typically applies to the case of a spouse of a US citizen who entered the US illegally and without inspection by Customs and Border Protection.
Prior to the enactment of the waiver law, this person would be obliged to travel back to his or her home country for the visa interview at the US embassy there,and also apply for a waiver while there. Under the new rules, the applicant applies for the waiver herein the US. without leaving the country, and the USCIS will make a determination on the application here. If the waiver is granted, the applicant can travel abroad and return to the US within days after the visa interview with a green card. The three- ten year bar does not apply.
Waivers for fraud or crimes are not included in this program. If the applicant has been convicted of serious crimes, or has committed immigration fraud, it is best not to apply for a waiver.