U.S. Citizenship and Immigration Services (USCIS) Law and Legal Definition

The United States Citizenship and Immigration Services (USCIS) is the government agency that oversees lawful immigration to the United States of America. It is a part of the Department of Homeland Security (DHS). The USCIS establishes policies and priorities to improve immigration services and ensures that no one who is a threat to national security is admitted to the U.S. USCIS is charged with processing immigrant visa petitions, naturalization petitions, and asylum and refugee applications as well as making adjudicative decisions.