A recent Oregon Government Standards and Practices Staff Opinion (07S-005) is a useful vehicle for explaining some basics of legal research to the novice legal researcher. And if you’re not a novice researcher, but are an Oregon government employee, you might want to read the opinion or ask your supervisor, manager, or HR or legal department representative.
In a nutshell, there are primary sources of law and there are secondary sources. Primary sources of law (not to be confused with what historians mean when they talk about primary sources) refer to actual laws, e.g. statutes, cases, and administrative laws. There are also constitutions, but it is the administrative laws that give new researchers the most difficulty. The executive branch can be very creative when making law (as can be seen in the most recent Vice President: Executive v. Legislative argle-bargle).
Years ago when I taught administrative legal research to law students I would sometimes take a story from the newspaper (the Washington Post on the latest goings on in the Executive Branch was always filled with good teaching examples) and highlight the dozens of “administrative documents” that were referred to – sometimes in one story. I’d then challenge the law students to figure out what the documents were and where to find them. (This was pre-web days so it was a little more difficult than it is now – but only a little.)
Administrative laws can include (and this is not a comprehensive list): regulations, rules, directives, guidances, letters, opinions, orders, investigations, guidelines, memoranda, actions, acquiescences, rulings, pronouncements, notices, opinions, policy statements, implementation plans, determinations, releases, and … surprise, surprise, Oregon GSPS opinions, such as 07S-005.