Technically, model rules are not primary authority until they are adopted by a state. However, since they serve as the origin of many state rules, they are included on this page.
American Bar Association: Center for Professional Responsibility: The Center provides national leadership in developing and interpreting standards and scholarly resources in legal and judicial ethics, professional regulation, professionalism and client protection.
ABA Model Rules of Professional Conduct: The ABA Model Rules of Professional Conduct were adopted by the ABA House of Delegates in 1983. They serve as models for the ethics rules of most states. Before the adoption of the Model Rules, the ABA model was the 1969 Model Code of Professional Responsibility. Preceding the Model Code were the 1908 Canons of Professional Ethics (last amended in 1963). The ABA offers an Annotated Model Rules of Professional Conduct (ABA eighth edition). This is also available on Westlaw at Home > Secondary Sources > Texts & Treatises > ABA Annotated Model Rules of Professional Conduct.
ABA Standing Committee on Ethics and Professional Responsibility: Since 1908 the Association's Ethics Committee has focused its efforts on the development of model national ethics standards for lawyers and the judiciary and the drafting of ABA Formal Ethics Opinions interpreting and applying those standards.
Charts Comparing Professional Conduct Rules: Charts for each state comparing adopted rules to the Model Rules.
ABA Model Rules Subject Guide: 25 page PDF document linking subjects to the rules.
ABA Ethics Opinions. Only most recent opinions are freely available unless you are a member of the ABA Center of Professional Responsibility. Otherwise you must pay to download or receive the opinions. However, these opinions are not searchable. Fully searchable versions are available on Bloomberg Law > Brows (Upper Left) > Litigation Analytics > Litigation Resources > ABA Bloomberg Law Lawyers Manual on Professional Conduct.
Missouri Supreme Court Rules Governing the Bar and Judiciary : These are the collective rules of the Missouri Supreme Court regulating the Bar and the Judiciary. Individual rules are cited as "Rule ___"; for instance the Rules of Professional Conduct are cited as Rule 4- #. #.
Formal Opinions of the Missouri Supreme Court Advisory Committee: The formal opinions and informal advisory opinions through June 30, 1994 are included in a deskbook entitled Missouri Advisory Opinions published by The Missouri Bar in 1995. A supplement to the deskbook was published in 1996. Opinions included in the deskbook and supplement are indexed by topic and include an annotation to the particular rule(s) involved. The book is no longer being published; however, you may search an electronic version of the deskbook and supplement and formal opinions published since 1996, but you will have to establish a free, non-member account as a student.
Informal advisory opinions are issued by the Legal Ethics Counsel under Rule 5.30. The Legal Ethics Counsel only issues opinions to attorneys for their own guidance involving an existing set of facts. Informal advisory opinions cannot be issued on hypotheticals or regarding the conduct of an attorney other than the one asking for the opinion.
Missouri Supreme Court Orders : Some, but far from all orders, deal with professional conduct issues. For example, Order dated December 1, 2015, re: Rule 15.05 Continuing Legal Education Requirements.
Attorney Disciplinary Information : Missouri Supreme Court Office of Chief Disciplinary Counsel.
See for example Missouri Supreme Court Rules of Prof. Conduct Rule 4-1.1 dealing with competence. Vernon's provides:
Link to Westlaw Next's Missouri Supreme Court Rules Governing the Missouri Bar and the Judiciary.
Title XXXII, Chapter 484 ("Attorneys at Law") is the code section of RSMO that governs attorneys. Link to web version of code.
An annotated version is available on Westlaw, which has Vernon's Annotated Code.
Westlaw: Home > Statutes & Court Rules > Missouri Statutes & Court Rules > Title XXXII. Courts > Chapter 484. Attorneys at Law
Veronon's is also available on the ground floor of the library and on the first floor. Ask a librarian to point it out.
In searching case law, it is extremely helpful to search by topic and key number. Topic number 45, Attorney and Client, and 311H,, Privileged Communications & Confidentiality, are probably most relevant in narrowing search results. Notice in the image below that Missouri and Federal cases have been selected. Any jurisdiction can be selected.