Immigration law refers to the rules established by the federal government for determining who is allowed to enter the country, and for how long. It also governs the naturalization process for those who desire to become U.S. citizens. Finally, when foreign nationals enter without permission, overstay their visit, or otherwise lose their legal status, immigration law controls how the detention and removal proceedings are carried out.
The U.S. Constitution grants Congress the exclusive right to legislate in the area of immigration. Most of the relevant laws, including the Immigration and Nationality Act (INA), are found in Title 8 of the United States Code. State governments are prohibited from enacting immigration laws. Despite this, a handful of states recently passed laws requiring local police to investigate the immigration status of suspected illegal aliens, creating some controversy.
Three federal agencies are charged with administering and enforcing immigration laws. Immigration and Customs Enforcement (ICE) investigates those who break the law, and prosecutes offenders. U.S. Citizenship and Immigration Services (USCIS) handles applications for legal immigration. Customs and Border Protection (CBP) is responsible for keeping the borders secure. All three agencies are part of the Department of Homeland Security.
Generally speaking, people from foreign countries obtain permission to come to the United States through a visa approval process. Visas are available for two purposes. Immigrant visas are for those who want to stay in this country and become employed here. These visas are limited by country-specific quotas. Non-immigrant visas are for tourists, students, and business people who are here temporarily.
Citizens of certain developed countries deemed politically and economically stable by the U.S. government are allowed to visit for up to 90 days without obtaining a visa. Known as the visa waiver program, this expedited system is primarily used by people coming here on vacation. It does not allow foreign citizens to work, go to school, or apply for permanent status. The visa waiver program is currently available to citizens of 37 countries.