In Custodia Legis: “The following is a guest post by senior legal reference librarian Beth Osborne. Recently, one of my colleagues from the blog team asked me if I knew of any “hidden treasures” at the Law Library of Congress that I wanted to mention in her recent post. Of course, I realized she was asking about something special—but perhaps often overlooked—from our wonderfully vast physical collection. However, my first thought was, “Congress.gov Action Codes!” So even though action codes did not quite fit the hidden treasures post, I thought I would take a few moments to talk about this powerful advanced search feature from Congress.gov. First—a brief background. Thousands of pieces of legislation are introduced in a two-year Congress, though relatively few are ever enacted into law. From the introduction of a measure to its passage, failure, or death, many different legislative actions can occur. Every bill or resolution that is uploaded to Congress.gov has information about the actions taken during the legislative process (for example, see the list of “All Actions” taken on S. 24, the Government Employee Fair Treatment Act of 2019). The Congress.gov data on legislative actions is largely pulled from the Congressional Record. Congress.gov enables researchers to search within certain categories of information (fields), and “legislative actions” is one such category. A task such as identifying all bills that were “introduced in the House of Representatives” is easy because that action is available from the left-hand menu as you look at a list of search results. However, if you want to craft a search based on less common legislative actions, or based on multiple legislative actions, using action codes in the advanced search feature may work for you. Action codes are numerical codes assigned to certain types of legislative actions. One benefit that action codes have over keywords is that they efficiently encapsulate similar actions described in different ways. For example, if you wanted to know how many bills had received floor consideration in the House, you could do a keyword search for every word or phrase that conceivably qualifies as a floor action (such as taking up, amending, debate, voting, passage, amendments between the chambers, conference actions, etc.). But, this would be an unwieldy and inefficient search. Instead, you can execute your search using the action code that represents “house floor actions” (actionCode:7000) and quickly capture all variants of floor actions that have taken place in the House. To use action codes, start on the page for advanced search of legislation and jump or scroll to the menus under “Action/Status.” You will likely need to scan the list of action codes to familiarize yourself with what is available and find the code or codes suitable for your search. Additionally, you can find a list of action search scope notes, which provide explanatory notes on action codes, as well as a large set of prepared queries featuring action code search fields. When using an action code, you need to use the prefix actionCode:XXXX, where XXXX is the code. If you are using more than one action code, you can use parentheses and connect them with a search operator…”