Metaphors abound in discussing how dramatically the issue of presidential impeachment has become central in U.S. political discourse: a simmering kettle boiled over, the Whistle Blower blew the lid off efforts to conceal scandalous (almost treasonous) presidential behavior. And everyone notes that what has been revealed is almost certainly matched by information that will come out sooner rather than later. It’s not possible to summarize the state of play because relevant events occur almost hourly. Here I’ll offer a primer on presidential impeachment in the United States for readers who might not be familiar with the basics, then offer some comments about presidential impeachment in comparative constitutional law.