President Donald Trump had not even taken office before critics who considered him dangerous began imagining how to get him out. One idea floated from the very start was the clause in the Constitution permitting the removal of a president deemed unable to discharge his duties. “Like so much with this president, it’s quite literally without precedent,” said Russell L. Riley, a presidential historian at UVA’s Miller Center. “To anyone’s knowledge, we’ve never been anywhere close to this situation before.”