It is no secret that political power in the United States and elsewhere has, overall, shifted to “the executive” and away from legislatures. There may be debate about whether this is a product of willful “overreaching” by executives or whether, within the United States, Congress has instead willingly ceded power by engaging in what Justice Cardozo in 1935 called “delegation run riot.” The concern about executive power has perhaps become heightened in the aftermath of the Trump presidency—just as Boris Johnson, with his own defiance of some of the “conventions” that are essential to the British constitutional order, is provoking debate in Great Britain.