How The Supreme Court Heightens Voter Polarization

A structural deficiency in American politics

It is no secret that the Supreme Court is an important institution: it lays the foundation for US law as the highest court in America, deciding cases that affect the lives of millions of people. In the last few years it has heard high profile cases on gerrymandering, healthcare, and immigration to name just a few of the issues on the docket.

Voters are smart. They know this and understand that the president nominates justices while the Senate confirms them, which is why it is such an important issue in elections. In 2016 the Supreme Court outranked civil rights, the environment, and abortion as issues. In fact many people voted for Trump specifically because of the Supreme Court vacancy, ignoring the realities of his campaign.

How these contentious issues play out in government is often decided through the Supreme Court, which is especially true when congress grinds to a halt in periods of divided government.

As a result the single most impactful thing a voter can do to push their agenda is frequently to elect a president who will then nominate a judge or a senator who will confirm a nominee that shares their ideology. And because justices have no term limits, nominating one can have a decades long impact.

The way we nominate Supreme Court justices, and the power that these justices hold, dramatically heightens the cost of losing elections. Rather than focusing on the set of candidates in an election and their policy views, many voters rationally focus on which candidate is more likely to support a Supreme Court justice that matches their views. This heightens voter polarization as today the two parties are split on almost every issue, making which party controls the Supreme Court able to cement their ideology in American law for decades.

As local governments increasingly start to pass laws centered around controversial culture war issues like transgender rights, this salience only increases. Any challenge to the constitutionality of local laws has the chance to work its way up to the Supreme Court, which can then set the legal precedence for the entire nation. It is no wonder that conservatives are trying to use their majority on the court today to overturn Obamacare and Roe v. Wade.

And we know the ideology of each justice on the Supreme Court is incredibly important to how cases are decided. In any standard hearing of a case, there are nine justices who vote to affirm or reverse the lower court’s ruling on a given case. The outcome of the court will be an affirmation if a majority of justices affirm and a reversal if a majority of justices reverse.

The table below shows the likelihood of a justice voting for the liberal outcome of a case split by justice ideology (as defined by a justice’s Martin-Quinn score) and whether the case was on the front cover of the NY Times, a measure of its lasting significance. In both cases conservative justices are 41% likely to vote for the liberal outcome while liberal justices are 69% likely if it is not on the front page and 80% likely if it is.

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Source: Supreme Court Database; Martin-Quinn scores

And note that while a justice’s ideology does drift liberal over time, it typically doesn’t drift enough to change them from a conservative to a liberal, so which side they start out on is effectively where they stay during their appointment.

As a result how liberal/conservative the median justice can essentially decide the outcome of a given case as that signals where the opinion of a majority of justices lie. If the median justice is liberal, then the majority of justices hold liberal views while if the opposite is true, then the majority hold conservative views. The intuition is the same as that of swing voters deciding elections.

Conservatives have often understood all this more than liberals. They have set up an entire apparatus to prepare and select judges for the Supreme Court and used the issue to turnout voters. The effectiveness of these operations speaks for itself as the Supreme Court has most often been a conservative leaning institution.

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Source: Martin-Quinn scores

Only three time periods stand out as being majority liberal: the late 1930s, 1960s, and Obama’s last years in office from 2014 to 2016. It is not a coincidence that these periods saw the expansion of civil rights with, for example, the Warren Court outlawing racial segregation in the 1950s/1960s and the legalization of gay marriage in 2015.

This incentive for voters to focus on potential Supreme Court nominations at the expense of actual candidate policy in both presidential and senate elections is far from ideal. Voters should cast ballots on the merits of how a candidate will materially affect their livelihood instead of whether they stand a chance to pass on their preferences through court rulings.

Looking ahead to 2020, this issue is going to remain at the top of many voter’s minds. Here is the current set of justices with their Martin-Quinn Score (again more negative means more liberal and more positive means more conservative) along with their age.

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Source: Supreme Court website

It is possible that over the next eight years that two justices on the liberal side will retire (Stephen G. Breyer and Ruth Bader Ginsburg). Whichever party gets to replace them will dramatically reshape the court either making it far more conservative or maintaining its current ideological tilt. Adding two conservative justices could very well make Neil Gorsuch the median justice, cementing him as the swing vote.

The 2020 election therefore is very likely to have a decades long impact on a range of policy issues that last far past the actual winner’s time in office.

A better functioning Democracy would be structurally set up to decouple the salience of choosing a Supreme Court justice from the result of president and senate elections. There are numerous policies to achieve this ranging from term limits to adding a bipartisan merit selection committee. America needs to consider these and other reforms in order to restore balance to the political system. The process today leaves the selection of judges directly exposed to the polarized electorate, which in turn exacerbates voter polarization as many realize the stakes of each election.

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