An ethics opinion ('advisory opinion") is written by the American Bar Association or by a state or local bar association, in response to an attorney request for advice.
Court cases involving legal ethics can be an attorney disciplinary proceeding, legal malpractice action, or involve sanctions over a court rule, such as Fed. R. Civ. P. 11, 26 or 37, or involve a claim of ineffective assistance of counsel in a criminal case.
The webpages of various state bar associations contain ethics opinions from that state. The American Bar Association has its advisory opinions on its website.