The election of Donald Trump presents new and unchartered challenges to those of us who support constitutional democracy. From Trump’s cavalier attitude towards Russian electoral interference, to his Presidential appointments of people clearly hostile to constitutional checks, to his dismissal of conflict-of-interest charges, it is clear that American constitutional democracy is in peril. While many of us will be engaged in looking to new ways to counter Trump’s threat, we would also do well to look to history, in particular to the wisdom of constitutional framer James Madison and his theory of interposition.

In 1798, Congress passed the famous Alien and Sedition Acts. These four bills made citizenship more difficult for new immigrants, gave the President expansive deportation powers, and turned criticism of the federal government into a criminal act. (Sound familiar?) In response, James Madison wrote a series of resolutions ultimately adopted by the legislature of Virginia. In the Virginia Resolutions of 1798, Madison offered the nuanced theory of “interposition” in which states could (collectively) intervene to protect state citizens against unjust federal laws.

As we collectively work to envision the myriad responses necessary to protect our constitutional democracy against Trumpian authoritarianism, we should consider how interposition might be an effective check on federal power.

The initial response from some people, especially on the Left, might be to resist interposition (and states’ rights arguments in general) due to their dubious past. As is well known, southern states marshalled states’ rights arguments to protect slavery and segregation. Southern apologists like John C. Calhoun and George Wallace employed states’ rights arguments to defend slavery and later Jim Crow laws throughout the South. Quite recently, states’ rights have been reintroduced to argue against civil rights on issues such as marriage equality, bathroom access, and immigration. Notably, in Shelby v. Holder, Chief Justice John Roberts reintroduced a version of states’ rights, founded on the concept of “equal sovereignty,” to strike down the core sections of the Voting Rights Act. In short, states’ rights have not been a friend of civil rights for most of American history.

Yet with the election of Donald Trump, everything changed. No longer is the federal government a likely defender of constitutional protections. In fact, the federal government is likely to be perverted into a direct threat to fundamental constitutional rights. Therefore, we would do well to consider how interposition might serve as a vital form of resistance to a federal government bent on undermining our constitutional democracy. For that, it’s worth turning to the primary author of the Constitution, James Madison.

Madison had little confidence that political leaders would act altruistically and limit their own power. Instead, he envisioned a system in which self-interested politicians would be confronted by other, equally self-interested politicians. Madison’s system of “checks and balances” was both horizontal (separation of powers) and vertical (federalism). These dual protections were baked into the Constitution itself: in the multiple and somewhat independent branches within the federal government, in the process by which it was adopted (by states, not directly by citizens) and the reservation of powers to states found in the 10th Amendment.

Madison argued that the fundamental responsibility for states was to protect the rights and freedoms of citizens, even if that meant resisting the federal government. For Madison, “the states … have the right, and are in duty bound, to interpose for arresting the progress of the evil, and for maintaining within their respective limits, the authorities, rights and liberties appertaining to them.” Madison advances the theory of “interposition” in which states serve as the institutional protection for citizens against unjust federal laws. States must exercise their (albeit limited) sovereignty to protect the rights and liberties of citizens. In effect, interposition argues that states, along with the federal government, have the Constitutional authority and duty to protect and promote justice, security, welfare and liberty. States, at times, are better able to fulfill this constitutional duty than the federal government. This is one of those times.

If (when?) the federal government under Trump threatens the liberty or general welfare of “the People,” makes our nation more insecure, or violates principles of justice, the states representing the people can (should?) interpose to protect their citizens. Trump and the Republican Congress has made clear that they intend to pursue a series of laws that threaten fundamental rights, laws that will likely grant the President advanced powers to criminalize criticism and deport immigrants — an Alien and Sedition Acts for the 21st Century, if you will. We are likely to see, in Madison’s words, the exercise of power that “ought to produce universal alarm” because it threatens the “right of freely examining public characters and measures, and of free communication among the people thereon.” States and the local governments chartered therein will need to interpose to protect citizens from these threats.

How can interposition be operationalized? First, states with supportive legislatures (e.g., California, Oregon, Illinois and several of the northeastern states) can pass legislation specifically to protect citizens from unjust federal laws. These states should act in concert (as Madison envisioned) to pass comprehensive laws interposing themselves between their citizens and the federal government. Declaring themselves sanctuary states and refusing to support a 21st Century version of the Alien and Sedition Acts would be one example, as California has recently done. The Attorneys General of these states can also sue the federal government to stop unjust laws, as Maura Healey has threatened to do.

In states with Democratic Governors and/or Attorneys General but with an uncooperative legislature (e.g., Minnesota, Colorado, Louisiana, and Washington) interposition will likely be led by the executive branch. In these states, for example, the Governor can unilaterally direct the state’s police and National Guard to refuse to enforce federal immigration laws. These state Governors can again join together to share successful strategies to interpose themselves and protect their citizens. As well, state Attorneys General can sue the federal government to stop unconstitutional action.

Finally, in so-called “red states,” successful resistance will have to be even more localized. While cities and counties do not have formal constitutional sanction, these local jurisdictions certainly function within the federalist system and arguably can make interposition claims based on their responsibility to protect citizens’ rights. The sanctuary city movement is emblematic of this effort. Grounding this movement in interposition will give it vital constitutional authority.

Interposition will not stop Trump and the threat to constitutional democracy. But embracing a new 21st Century interposition is an essential intellectual shift. While it may be difficult to comprehend fully that the federal government will no longer be a partner in the fight for justice, facing this fact and turning to the other institutional protections that Madison helped create may be the only way to preserve our constitutional democracy.