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?