During a Supreme Court hearing this morning, John Sauer, representing the former president, argued that each of these actions could be understood as an “official act” of the president, and that no current or former president may be charged with crimes for doing them. Sauer repeatedly complained that no president had faced a criminal prosecution before Trump, an argument that seemed to find favor among conservative justices. That wouldn’t settle the matter, though; if the Court does conclude that a president enjoys criminal immunity for official acts, then the question becomes what Justice Clarence Thomas asked near the very outset of the hearing: “How would we determine what an official act is?”