Hypothetical questions can help facilitate conversations on judgments about the perceived likelihood or potential consequences of an event or an action. They can also help reveal hidden or flawed assumptions. Supreme Court justices, for instance, often use hypothetical questions to test the outer boundaries of what the advocate is asking the court to declare and of what the court may have to decide. Such questions are also permissible in trials and depositions. Lawyers often use hypothetical questions to help frame facts for the jury. This column aims to clarify the circumstances under which hypothetical questions are permissible for both lay and expert witnesses.