Immigration law in the United States generally includes the rights and obligations of persons who are not U.S. citizens to temporarily visit or more permanently reside in the U.S.—and for federal and state governments to enforce immigration laws regarding visitors and residents.

Most immigration law consists of federal statutes and regulations—but many state laws impact both legal and illegal immigrants—including employment checks, E-Verify, law enforcement, driver's license requirements, public benefits restrictions, and more.

In Montana (MT), as in all states, immigration law is primarily governed by federal statutes and regulations, as the authority to regulate immigration is a federal power. This includes laws pertaining to visas, green cards, asylum, deportation, and citizenship. State laws in Montana may impact immigrants in various ways, such as through employment verification requirements. Montana employers are required to verify the employment eligibility of their employees, and while the use of the federal E-Verify system is not mandated statewide, it is used by some employers voluntarily. Law enforcement in Montana may also play a role in immigration enforcement, particularly when it comes to cooperation with federal authorities. Additionally, Montana has regulations regarding driver's license requirements and public benefits, which can affect both legal and illegal immigrants. For example, Montana may have specific criteria for issuing driver's licenses to non-citizens or may restrict access to certain state-funded public benefits for those without lawful immigration status.