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 Idaho, as in all states, the definition and regulation of unauthorized or undocumented resident immigrants are primarily governed by federal law, specifically the Immigration and Nationality Act (INA). Unauthorized immigrants are those who have entered the United States without proper inspection or have overstayed their visas. In Idaho, these individuals do not have legal status, but they may be eligible to apply for certain forms of relief under federal law, such as adjustment to lawful permanent resident (LPR) status. However, until they successfully adjust their status and obtain a green card, they remain unauthorized. Temporary Protected Status (TPS) beneficiaries are granted temporary lawful presence and work authorization, but they are not considered lawful permanent residents. It's important to note that while state laws may impact certain aspects of immigrants' lives, such as access to state services or law enforcement practices, immigration status and enforcement are primarily matters of federal jurisdiction.