One of the most important purposes of U.S. immigration law is to help U.S. citizens and other lawful permanent U.S. residents reunite with family members who presently reside overseas. However, this immigration goal does not mean that every relative of a U.S. citizen or permanent resident will be eligible for a family-based U.S. green card. Before you promise a relative who lives outside the United States that you can help them secure a U.S. green card, ensure that you are sufficiently knowledgeable about the stringent U.S. immigration law guidelines.