After the creation of the Department of Homeland Security in 2003 after the September 11 attacks, the enforcement of immigration laws was transferred from the Immigration and Naturalization Service(INS) to the Department of Homeland Security. Enforcing the immigration laws, the Secretary of Homeland Security collaborates with the Attorney General, the Department of State through its Secretary, officers, and diplomatic or consular officers. 8 U.S.C.A. § 1103.
For the primary sources, you will look at statutes, regulations, federal decisions, and administrative decisions. You will learn selective primary sources and their application throughout immigration law courses. The structure of statutes was mainly established by the Immigration and Nationality Act of 1952 (INA), so called McCarran-Walter Act in 1952, subsequently revised and amended by different acts and treaties including NAFTA. And the regulations are mainly codified in Title 8, 20, 22, and 28 of the Code of Federal Regulations(CFR) and are issued by a variety of governmental bodies including the Department of Homeland Security(DHS), the Executive Office for Immigration Review (EOIR), the Department of Justice, the Department of Labor, the Department of Public Health Service, the Department of Justice, etc. Furthermore, there are cases by federal courts and administrative decisions by administrative judges, the Board of Immigration Appeals(BIA), the Office of Chief Administrative Hearing Officer(OCAHO), the Administrative Appeals Office(AAO), INS General Council, the Board of Alien Labor Certification Appeals(BALCA), etc.
You may also want to look at secondary sources such as looseleaf services, treatises, journals, etc. These will be the best starting point for your research because these provide you with current awareness services and references to statutes, regulations, and any decisions relevant to your specific issues. You may be frustrated by the complexity of immigration sources if you are simply looking at the annotated statute, following the references to regulations and spending enormous time in finding any relevant federal and administrative decisions. The best research skill in the immigration law is drawing a big regulatory landscape based on each topic and key term such as removal, deportation, criminal offense, visa application, etc. by the assistance of the secondary sources.
Additionally, if you are a practitioner preparing various documents for your client’s visa application and the change of his/her status, you may want to go to websites of various administrative bodies such as USCIS(U.S. Citizenship and Immigration Services under the Department of Homeland Security), the U.S. Department of Labor, the U.S. Department of State, etc.