Federal immigration law as the gatekeeper of the nation regulates entry, exit and duration of stay of individuals in the United States. It also helps to decide if any individual is an alien. Immigration law also deals with the rights and duties of aliens and prescribes the modes by which they can become naturalized citizens with rights of citizenship.
The Congress has legislative powers over immigration. The President can only formulate policy on refugees. The Immigration and Nationality Act of 1952, which has been amended from time to time, is the basic immigration law of the US. States have limited law making power on immigration mostly restricted to providing for sentences for illegal entry.
An alien is an individual who is not a citizen or national of the US. Aliens can be of different types, such as, resident or non resident, immigrant or nonimmigrant, documented or undocumented aliens etc.
Immigration policies are implemented either by allowing or denying visas, which are broadly of two types, immigrant and nonimmigrant visas.
Immigrant visas permit the holder to stay back and work in the US permanently and eventually apply for US citizenship. The maximum number of immigrant visas that can be issued annually is limited to 7, 00,000 only. Many immigrant visas also have per country ceilings.
Nonimmigrant visas are of eighteen main categories and are issued to tourists, students and business visitors. The number of nonimmigrant visas in most of these categories is not limited. Only few categories of nonimmigrant visa holders are allowed to work in the US.
An alien can apply for lawful permanent residence (LPR) or ‘green card’ either along the path of immigration through a family member or through employment in the US. (More http://www.uscis.gov/greencard)
An individual who is neither a citizen nor a lawful permanent resident of the US has to obtain ‘Employment Authorization Document’ (EAD) to work in the US.
Under the provisions of the Child Citizenship Act, which the Congress passed in 2000, any child below 18 years adopted by a US citizen and immigrating to the US can acquire immediate citizenship.
The Congress enacted the Immigration Reforms and Control Act of 1986, which provides for rigorous criminal sanctions and prosecutions against employers hiring illegal aliens and denies the benefits of federally funded welfare schemes to illegal aliens. However, some aliens were selectively legitimized under it through an amnesty scheme.
The Immigration Marriage Fraud Amendments of 1986 discourages grant of citizenship to aliens getting married to Americans for becoming citizen.
The Antiterrorism and Effective Death Penalty Act and Illegal Immigration Reform and Immigrant Responsibility Act specifies criminal activities for which immigrants including green card holders are liable to be deported or suffer mandatory detention.