In the United States, the area of "Immigration Law" refers to the laws and enforcements dealing with immigration into the United States and the deportation of individuals from the United States.
Immigration law is primarily dealt with at the federal level (although, some states have passed laws to enforce existing federal immigration laws). As such, this entry deals exclusively with federal immigration law.
Federal immigration law determines whether a person is an alien (which is the term used by the Internal Revenue Service), the rights, duties, and obligations associated with being an alien in the United States, and how aliens gain residence or citizenship within the United States. It also provides the means by which certain aliens can become legally naturalized citizens with full rights of citizenship. Immigration law serves as a gatekeeper for the nation's border, determining who may enter, how long they may stay, and when they must leave.