Searchable since 1983. Includes laws establishing an agency and laws an agency administers. Difficult to search because of length search results. It is probably better to browse the list of titles. Identify the agency web site.
Most web sites describe missions and programs.
Some also provide agency history. Do not expect an agency web site to discuss its own politics. Search for Title 42. Both types of regulations include the background of the proposal and a citation to the authorizing law. Enter through Bills, Laws and Regulations .