The unauthorized or undocumented resident immigrant population is defined as all foreign-born non-citizens who are not legal residents. Most unauthorized residents either entered the United States without inspection or were admitted temporarily and stayed past the date they were required to leave.

Unauthorized residents applying for adjustment to lawful permanent resident (LPR) status under the Immigration and Nationality Act (INA) are unauthorized until they have been granted lawful permanent residence (a green card)—even though they may have been authorized to work. Persons who are beneficiaries of Temporary Protected Status (TPS) are not technically unauthorized.

In Alabama, as in all states, the unauthorized or undocumented resident immigrant population is subject to federal immigration laws, as immigration is a matter of federal jurisdiction under the U.S. Constitution. The Immigration and Nationality Act (INA) governs the status of all immigrants, including those without proper documentation. Unauthorized immigrants are those who have entered the U.S. without proper inspection or overstayed their visas. In Alabama, state laws such as HB 56, known as the Alabama Taxpayer and Citizen Protection Act, have been enacted to discourage the presence of undocumented immigrants, although parts of this law have been challenged and blocked in court. Unauthorized residents in Alabama may seek an adjustment of status to become Lawful Permanent Residents (LPRs), but they remain unauthorized until they receive their green card. Temporary Protected Status (TPS) holders are not considered unauthorized, as TPS is a temporary legal status granted by the federal government to eligible nationals of designated countries.