As a general rule, persons who entered the United States illegally (i.e. snuck across the border or otherwise entered without inspection by an immigration official) are not entitled to apply for lawful permanent residency in the U.S. by utilizing the adjustment of status process. As a result there are many undocumented and unlawful immigrants who are in the U.S. and despite being married to a U.S. Citizen have very few good options for legalizing their status. This is because of a law known as the 3/10 year bar that provides that anyone who enters the U.S.

The Affidavit of Support is an import part of all family-based immigration cases. In order to be admissible as an immigrant to the Unites States the prospective immigrant must establish that he or she will not become a "public charge." In plain terms this means they have to establish that they won't rely on the government for public assistance. The primary method for establishing this requirement is through the use of an Affidavit of Support. In fact, the affidavit of support is required in most all family-based immigration cases.

Adjustment of Status is an immigration process that allows a non-immigrant who is physically present in the U.S. to "adjust" his or her status to that of a lawful permanent resident. This process is most commonly used for non-immigrants in the U.S. to change their status to lawful permanent residents if they have been approved for an employment-based immigrant visa or a family-based immigrant visa.