There are three main types of US institutions overseeing the creation and defense of law, and consequently there are three main legal categories of US Law.
Statutory Law (law generated by federal and state congresses/legislatures which becomes part of Federal and State Constitutions and Legal Codes)
Case Law (Summaries of Court cases establishing legal precedents based on interpretations of statutory law)
Regulatory Law (issued by the Federal Department of Justice or an equivalent State agency that are overseen by Attorney Generals)
In addition, there are large bodies of secondary literature discussing all three types of laws and related interpretations and legal process found in law journals.
Each form of US law can be found in different resources, and some of these include useful content for international law.
The Westlaw Database includes content in all forms of law – but is especially useful for Statutory and Case Law. This is because it includes annotations about when portions of statutes or case law have been
The recommended sources to find information related to federal regulations are the govinfo.gov website or the HeinOnline database. Both provide access to the Federal Register (which is published daily and therefore documents proposed regulations and changes/updates to those regulation) as well as the Code of Federal Regulations (CFR) which publishes approved and adopted (i.e. final regulations only) annually. However, it is important to note that there is now an electronic edition of the CFR that is updated daily based on final recommendations documented in the Federal Register. Westlaw includes the CFR only, not the Federal Register.
In addition to its primary source content (laws themselves), Westlaw includes important secondary source material, including reference tools such as encyclopedias and journal articles published in law reviews. Hein Online provides access to additional periodical material.
HeinOnline also provides very useful additional content:
The linked Essay may also be helpful to understand current (2018-) Logistics and Realities of Regulatory Reforms to Deter Immigrants from Soliciting and Securing Asylum (focused on Central American migrants, but applicable to many other ethnic and national individuals and groups)