Beyond the obvious — that liberals need some way to respond to President Trump as he moves to fill the Supreme Court vacancy left by the death of Ruth Bader Ginsburg — what does it mean that mainstream Democrats are considering once unthinkable ideas like adding seats to the court?

Perhaps, as some conservatives argue, it’s evidence that Democrats aren’t as committed to the norms of American democracy as they claim to be. Perhaps, as some hopeful liberals believe, it’s evidence that Democrats are finally beginning to buck the timid institutionalism that so often shapes their politics.

I take a different perspective. If Democrats are willing to treat a Republican-dominated Supreme Court as a partisan and ideological foe, if they’re willing to change or transform it rather than accede to its view of the Constitution — two very big ifs — then they’re one important step along the path to challenging judicial supremacy, the idea that the courts, and the courts alone, determine constitutional meaning.

The Supreme Court has the power to interpret the Constitution and establish its meaning for federal, state and local government alike. But this power wasn’t enumerated in the Constitution and isn’t inherent in the court as an institution. Instead, the court’s power to interpret and bind others to that interpretation was constructed over time by political and legal actors throughout the system, from presidents and lawmakers to the judges and justices themselves.

If judicial supremacy was constructed, then it was also contested, and that contestation is a recurring part of American political life. “The judiciary is not the sole guardian of our constitutional inheritance and interpretive authority under the Constitution has varied over time,” the legal scholar Keith E. Whittington writes in “Political Foundations of Judicial Supremacy: The Presidency, the Supreme Court and Constitutional Leadership in U.S. History.”

Fights over the power and authority of the judiciary have been especially fierce at those points in American history when an ambitious president atop a rising coalition has tried to remake the political order according to that coalition’s understanding of the Constitution. These presidents, Whittington argues, “achieve ‘greatness’ through their ability to tear down the inherited but discredited regime and raise up a new one in their own image. They ‘reconstruct’ the nation by reinterpreting its fundamental commitments.”