Identify the Oregon code (Oregon Revised Statutes "ORS") section to find the relevant language you'd like to research.
The bracketed final sentence in the small print at the end of the statue is the statutory history. This history lists all the session laws that enacted, amended, or repealed the code section.
This history includes: (1) the year the law was passed; (2) the year of any amendment; (3) the session law chapter "c"; and (4) the section number of the session law chapter.
Tip: If your code section doesn't have a history line, it may have been enacted prior to 1953. Ask a librarian for assistance.
For example, the bracketed information that appears at the end of ORS 811.060, [2001 c.635 §5; 2017 c.388 1], means that the law was enacted and first appeared in chapter 635, section 5 of the 2001 Oregon Laws and was later amended by chapter 388, section 1 of the 2017 Oregon Laws.
If the code section that you are researching has many session laws listed in the history line, you'll need to determine when the specific language that interests you was added. The easiest way to do this is to look at every version of the code section for each year listed, including any renumbered code sections.
In the example below, a researcher would need to look at the ORS version from 2017, 2015, 2013, 2007, 2005, 2003, 2001,1999, 1997, and 1993 to determine in which year their language was added or amended.
Westlaw and Lexis both provide the current version of the law and archived versions of the ORS back to 1989 and 1991 respectively. In addition, both provide links to earlier session laws and annotations to law review articles. For more recent legislation, Westlaw links directly to the committee summaries, videos, and exhibits that are associated with a law, thus saving much time and effort. Lexis links to the session laws and provides markups of the changes.
HeinOnline has historical Oregon codes dating from 1853 to 1935. Use the Oregon State Statutes database.
The Boley Law Library has complete sets in print of all of the Oregon codes, Oregon session laws, and the Oregon House and Senate Journals: available in the Oregon section of the library.