The Immigration and Nationality Act (INA) came into existence in 1952, and serves as a way to restructure and code immigration law. Before the Immigration and Nationality Act, there was no organized location for statues concerning The Immigration and Nationality Act was created with the McCarran-Walter bill of 1952, and essentially contains regulations which govern immigration and citizenship. The Immigration and Nationality Act (INA) also outlines employment regulations for aliens, including information on employment eligibility verification, and consequences for employers who knowingly hire illegal immigrants.

The Immigration and Nationality Act defines the classification criteria for aliens, refugees, immigrants, non-immigrants, and citizens, in addition to containing information on the annual quotas for immigrant and non-immigrant visas. This body of law also officially defines the territories of the United States. On December 24, 1952 the Immigration and Nationality Act defined the United States to include Guam, and since then has included other territories into the United States such as the Commonwealth of the Northern Mariana Island, Puerto Rico, and the U.S. Virgin Islands. Since the terrorist attacks of September 11, the INA has undergone many revisions.

An example of a statue contained in the Immigration and Nationality Act is as follows: Derived from Sec. 101. [8 U.S.C. 1101]

• The term "alien" means any person not a citizen or national of the United States.
• The term "application for admission" has reference to the application for admission into the United States and not to the application for the issuance of an immigrant or nonimmigrant visa.
• The term "border crossing identification card" means a document of identity bearing that designation issued to an alien who is lawfully admitted for permanent residence, or to an alien who is a resident in foreign contiguous territory, by a consular officer or an immigration officer for the purpose of crossing over the borders between the United States and foreign contiguous territory in accordance with such conditions for its issuance and use as may be prescribed by regulations. Such regulations shall provide that (A) each such document include a biometric identifier (such as the fingerprint or handprint of the alien) that is machine readable and (B) an alien presenting a border crossing identification is not permitted to cross over the border into the United States unless the biometric identifier contained on the card matches the appropriate biometric characteristic of the alien.

An overview of the statues contained in the Immigration and Nationality Act is as follows:

• Definition of a United States alien, refugee, citizen, and other terms pertaining to U.S. immigration
• Annual limits placed on visa issuance (usually depends on immigrant classification, and country of origination)
• Statues governing the employment of aliens
• List of United States territories