Antonin Scalia’s untimely death instantly propelled the Supreme Court to the forefront of the 2016 election cycle. Republicans immediately refused to confirm anyone nominated by President Barack Obama, falsely claiming that an election-year appointment violates decades-long precedent. It now appears there will be a vacancy on the Court for a year or more.

The breakdown in the process to appoint Scalia’s successor is the latest evidence that America’s presidential system no longer works. Democrats are not free from blame, but it is largely Republicans who are responsible for the dissolution of many American political norms, through their abuse of the filibuster and their attempts to take the debt ceiling hostage, among other destructive tactics.

More significantly, this escalating chain of unprecedented violations over the past two decades is the logical culmination of having ideologically polarized parties in a presidential system built to operate upon norms and consensus. With polarization and the presidency’s winner-take-all nature, parties have tremendous incentive to eschew compromise and manipulate the process for partisan gain. Even Republican senators in states Obama carried appear to be hostile towards any likely court nominee, lest they earn a Tea Party primary challenger.

Spanish political scientist Juan Linz asserted in a seminal 1990 essay that presidential liberal democracies almost always collapse over the long term due to civil war, military coup, or a descent into illiberal dictatorship. Our own country has not been an exception; Abraham Lincoln’s 1860 presidential election victory set off a series of events that sparked the Civil War. Linz convincingly argued that parliamentary systems are more stable than presidential ones.

While our republic isn’t in danger of devolving into all-out war, another kind of disintegration is at work. How did we get here?

When conservative Southern Democrats became Republicans in the aftermath of the Civil Rights Act, our modern parties began to split into two distinct ideological groups (though one would become more extreme and homogenous than the other). This trend accelerated in the 1990s, when the Republican Revolution transformed Congress into a precursor of the hyper-partisan battleground it is today. Partisan polarization is now stronger than at any point since the Civil War, if not all of American history.

The 2000 Supreme Court ruling Bush v. Gore was also a watershed moment, when five partisan Republicans disregarded judicial norms and overturned a lower court ruling to install a fellow Republican as president. Suddenly, the Supreme Court revealed itself to be just another partisan institution, and control over that body would turn into a scorched-earth fight between the parties.

Under George W. Bush, Republicans used the Department of Justice to validate a slew of anti-voting rights laws that harmed Democrats. They appointed judges whose interpretation of voting rights and electoral law resembled that of sharply conservative Republican politicians, eventually leading to the Supreme Court gutting the Voting Rights Act in 2013. Myriad states changed their election laws to help cement Republican power, a development that would take on immense importance after the Republican wave of 2010.

The Supreme Court’s ruling in Bush v. Gore led many Senate Democrats to abandon the longstanding tradition of confirming qualified judicial nominees regardless of party. In 2005 most Democratic senators voted against confirming Bush’s two Supreme Court nominees. Samuel Alito’s confirmation succeeded in part because of the implicit threat that Republicans would curtail the Senate filibuster if the Democratic minority attempted to use that tactic to block him.

After losing Congress in 2006 and the White House in 2008, Senate Republicans abused the filibuster to impose a de facto supermajority threshold for all legislation and nominations, even on those who would have easily mustered the 60 votes for cloture. Never before had one party used this strategy, and Republicans did it with near-perfect party unity on major bills and nominations, giving Obama’s Supreme Court nominees very little support.

In 2013, Democrats changed the Senate’s rules to end the filibuster for executive and judicial nominees, with a notable exception for the Supreme Court. The next time one party controls both the White House and the Senate, it will be sorely tempted to eliminate the filibuster entirely to prevent any obstruction from the minority party.

Republican intransigence now has reached a boiling point. They will likely set a dangerous precedent where no party confirms the other party’s court nominees during divided government. Leaving Supreme Court seats vacant for extended periods can only further politicize and delegitimize the court in the public eye, while partially hobbling a crucial branch of our government.

This self-perpetuating cycle of partisan escalation and reaction is a key byproduct of the separation of powers. Both the president and Congress derive democratic legitimacy from voters, and when the two institutions are divided between two polarized parties, there is no democratic mechanism for resolving conflict. 

This defining defect of presidentialism is why the system so frequently breaks down. Partisans seek to expand the powers of the institution they control beyond established limits at the expanse of the other party’s branch of government—see the GOP’s many futile attempts to get Obama to gut his own signature health care law.

As a result, there are already signs of creeping illiberalism. The executive branch has increasingly expanded its own abilities through new executive actions and war powers. Republican state governments have passed restrictive voting laws, while rampant gerrymandering has likely locked Democrats out of the House for years even though they won the 2012 popular vote.

American politics shouldn’t have to be this way. Only a single European liberal democracy uses a full presidential system and instead most use the parliamentary system, where the legislature also holds executive power. This system better handles ideologically polarized parties by removing the institutional gridlock of divided government. Executive power does not flow solely through an individual selected in a winner-take-all contest. Early elections can resolve a legislative impasse and that prospect can induce parties towards compromise rather than face disgruntled voters. And with proportional representation, parties win parliamentary seats in relation to their overall popular vote share, meaning a single party is unlikely to win a majority and would thus need a coalition of parties to govern.

Of course, the United States will not become a parliamentary democracy anytime soon. But at the same time there is no reason to believe that the fight over Scalia’s successor will resolve the tensions inherent in our presidential system—indeed, it is likely to exacerbate this slow-motion crisis. At some point, more drastic measures may have to be considered. The irony is that our checks and balances have produced so much partisan gridlock that the only way we can amend our Constitution now is through reinterpretation by the Supreme Court.