Ethical rules (the Rules of Professional Conduct, or "RPC") regulate the legal profession and govern the conduct of lawyers, violation of which can subject lawyers to various forms of discipline, including censure, suspension to practice, and disbarment.
In a legal malpractice action in Washington, the jury may not be informed of the Rules of Professional Conduct (or the predecessor Code of Professional Responsibility) either directly through jury instructions or by the testimony of experts who refer them. Hizey v Carpenter, 119 Wash.2d 251, 830 P.3d 646 (1992). The court in Hizey held that these ethical rules do not create a cause of action, and rejected the plaintiff’s argument that violation of them should at least constitute admissible evidence of malpractice.
In Washington, experts on an attorney's duty of care may properly base their opinion on an attorney's failure to conform to an ethics rule. In so testifying, however, the expert must address the breach of the legal duty of care, and not simply the supposed breach of the ethics rules. Such testimony may not be presented in such a way that the jury could conclude it was the ethical violations that were actionable, rather than the breach of the legal duty of care. In practice, this can be achieved by allowing the expert to use language from the RPC, but prohibiting explicit reference to them.
Similarly, Oregon's ethical rules (also RPC) do not provide a private cause of action for legal malpractice. An act which constitutes a violation of Oregon's ethical rules may also constitute legal malpractice, but the source of the duty is independent.