More fundamentally, maintaining the right’s capacity to implement anti-majoritarian policies from the bench requires maintaining a norm against the more democratic branches of government intervening in the judiciary’s affairs. Congress has the constitutional authority to alter the number of justices on the Supreme Court, and it has done so six times since the republic’s inception. All that stands in the way of a Democratic president and Congress from legislating themselves a liberal Supreme Court majority are norms. And this is what’s actually at stake in the bizarre, mutually disingenuous procedural argument about election year Supreme Court appointments: McConnell wants to disguise the fact that he is subordinating norms of forbearance to the attainment of power, and Democrats want to expose this fact.

Of course, were a future Democratic government to violate the norm against court expansion, they would clear the way for their Republican successors to do the same. But a world in which Supreme Court majorities come and go with shifts in partisan electoral fortunes would be much less favorable to conservatives than a world in which a six-member right-wing majority reigns for a generation. In the former case, the end result is likely to be the weakening (if not outright destruction) of judicial review — which is to say, of the judiciary’s power to declare duly enacted legislation unconstitutional. This is an authority that the Supreme Court gave itself in Marbury v. Madison and is nowhere to be found in the text of the Constitution. For the vast majority of U.S. history, judicial review has served as a tool of reaction, one that allowed conservative forces to insulate the prerogatives of economic elites from democratic challenge. If Republicans get their way, it will serve that same function in the decades to come.