These sources give overviews of the law of professional responsibility and cite to primary materials, such as major statutes, rules, and cases.
Browse or search these sources to get an idea of the most controversial or widely-discussed legal ethics issues.
The State Bar of California has Rules of Professional Conduct and related rules, statutes and other materials on its web site.
Annotated Rules of Professional Conduct are included in West's and Deering's annotated California codes in print and online.
Here are some sources for the ABA Model Rules (with comments), as well as some additional materials with helpful information on the Model Rules.