Step 1) Check the history notes at the end of your CCR section. Note the date filed, the year and register number (e.g.filed 5-13-2009; operative 6-12-2009 Register 2009 No. 20).
Step 2) If no notes are at then end of your CCR section, try the end of the preceding section, the end of the first section in the article, or the end of the first section in the title.
Step 3) Use the history notes to find out the operative dates of the changes to the regulation. You can then look up these references in the appropriate year of the CCR (see superseded regulations). Sometimes this works perfectly. However, not all regulatory changes make it into the notes.
Step 4) If you can't find the earlier references using Step 3...Use the dates filed of your regulation to review the entries in the appropriate Regulatory Code Supplement (aka the Register). Use the references to the sections affected to locate the previous citation for your regulation, and then look at the official version of the regulation in the appropriate year of the CCR. Work backwards in the Regulatory Code Supplement for each earlier incarnation of the regulation.
Step 5) There is also a handwritten guide to the register of all the changes made to each title, by agency, from 1945 to 1990. Legislative Research, Inc. has made these handwritten cards available online. It's called the Magic Drawer. The only searchable text is the title information (search = Title 13). Then review the card entries. The entries do not list individual regulations, so you will have to search each register to see if your regulation was affected. However, you can cross-reference the card entries with the list of changes you have found with your previous search.
Step 1) Locate the current regulation in the CCR on Westlaw.
Step 2) Click on the History tab for Regulatory History