Immigration law - When someone applies for a passport, travels from his country of residence to another country, or seeks to enter another country for employment or school attendance, these actions are part and parcel of International Immigration law. This area of law is regulated by international law and is very closely associated with nationality law, which basically deals with a person's legal status as a citizen. Immigration law is not uniform throughout the world, but the United Nations International Covenant on Civil and Political Rights has decreed that all countries must allow entry to its own citizens.
U.S. Immigration law falls under the umbrella of the federal government and determines whether a person is an alien, as well as his legal rights, duties and obligations while in the U.S. An alien was defined by the Immigration and Nationality Act of 1952 (INA) as "any person who is not a citizen or a national of the United States." U.S. Immigration law further oversees all the processes under which aliens my enter the U.S., gain residence, and/or become a naturalized citizen, wherein they obtain full citizenship rights. It includes a regulatory body which deals with who may enter the U.S., how long visitors may remain and when they must be evicted.
Title 8 of the U.S. Code contains the U.S. federal Immigration Laws and 28 U.S.C. 1251 of the U.S. code describes the jurisdiction individual states have. Congress maintains total authority over U.S. Immigration, while the President's authority is restricted to refugee policy. The U.S. courts generally stay out immigration matters, unless constitutional rights are at issue.
The duties of enforcing U.S. Immigration laws are shared by different agencies. While many people are familiar with the INS (Immigration and Naturalization Service), it actually no longer exists, as it was replaced by the Department of Homeland Security (DHS) in 2003. Immigration and Customs Enforcement (ICE), U.S. Citizenship and Immigration Services (USCIS), and U.S. Customs and Border Enforcement (CBE) are the agencies within DHS which now handle the former duties of the INS - investigative responsibilities, naturalization, asylum, and permanent residence functions; and border patrol duties. While our consulates and embassies around the world are managed by the U.S. Department of State.