Lawyers are routinely admitted or authorized to practice in multiple jurisdictions, whether by bar admission, pro hac vice admission or other circumstances. But not all jurisdictions share the same ethical rules. Where conflicts arise, attorneys may be faced with a difficult question: Which ethical rules must the lawyer follow?

On March 1, the American Bar Association’s Standing Committee on Ethics and Professional Responsibility issued Formal Opinion 504, which provides guidance. The opinion relies on ABA Model Rule 8.5, which provides that, when a lawyer’s conduct is in connection with a matter pending before a tribunal, the lawyer must comply with the ethics rules of the jurisdiction in which the tribunal sits, unless the rules of the tribunal provide otherwise.