The U.S. governmental system consists of on three branches of government, the legislative, the executive and the judicial, in a system of checks and balances. The legislature passes laws, the executive branch administers or enforces the laws, and the judiciary interprets the laws. The law governing the immigration system within the U.S. is known as the Immigration and Nationality Act (INA). There are other laws that have implications related to immigration, but most key immigration matters are addressed within the INA. Changes to the immigration law usually involve amending the provisions of the INA.

Historically, and under the constitutional doctrine of preemption, only the federal government in Washington D.C. enacted legislation on the national issue of immigration. More recently, some states have become increasingly active in efforts to address immigration concerns at the state level. This has led to controversy and litigation regarding limits of state authority. 

At the federal level, elected representatives in the U.S. Senate and the U.S. House of Representatives comprise the federal legislature, known as the U.S. Congress. Congress only passes a small percentage of the many legislative proposals, or bills, introduced each year. Once approved by Congress, bills must still be presented to the President for final approval and signature. Without the President’s approval, a bill does not become law, unless Congress can agree to override the President by a sufficient majority. Passage of laws is a difficult process, therefore, particularly in controversial areas like immigration.

Once a bill is enacted into law, agencies like the USCIS and the U.S. Department of Labor become responsible for implementation and administration of the law. Part of this responsibility includes issuing regulations specifying the many details, nuances, and interpretations of the more general terms of a law. Proposed and final regulations appear in the Federal Register. The public has the right to comment on proposed regulations. The agency that issued the proposed regulation may choose to revise the regulation or not, based on public comment.