Article III of the U.S. Constitution both limits the reach of the Supreme Court and at the same time gives the Justices great power.  As the only branch of the federal government with life tenure, the judicial branch maneuvers oftentimes outside of public spotlight and so judges are not subject to the same public pressures as are actors from the two other branches.  While there are several mechanisms in place to check the power of the Supreme Court, these are also, for the most part, mere talking points.  Supreme Court Justices, for instance, can be removed from office through impeachment.  Only one Justice over the course of American history, however, Samuel Chase, was impeached. The House impeached Justice Chase in 1805 for showing political bias as a lower court judge.  The Senate acquitted Justice Chase though and he was not removed from office.

This brief dip in the history of the Court is designed to show that there are few external pressures designed to sway the Justices’ votes.  Instead the Justices are insulated within the federal government and command a wide array of subject matter in their purview.  Add to this the stagnant political process per House Representative John Boehner and the importance of Supreme Court Justices is even more pronounced.  Boehner described during the recent presidential election that, “[t]he only thing that really matters over the next four years or eight years is who is going to appoint the next Supreme Court nominees.”

The powers (and limits thereof) of Supreme Court Justices have created their own narrative over time.  The discussion about the importance of judicial restraint dates back at least to the 19th century as do calls for curbing the federal judiciary.  At the same time the Court has decided issues ranging from slavery to abortion to voting rights all of which had and have national implications for years to come.  Suffice it to say Supreme Court Justices wield significant power.  As each Justice has an equal vote in each case, though, the Justices in one sense have equally distributed power.

As surprising as it is to some, many of the Courts decisions are unanimous.  In unanimous votes, there is little power in the moves of individual Justices as several could dissent without changing the result.  As I have previously argued, though, cases decided by one vote make each Justice’s vote pivotal.  These are the cases where votes are at a premium as is the right to draft the Court’s majority opinion.  These cases across the Court’s history are this piece’s area of focus.

Since its inception, the United States Supreme Court has decided 1,705 cases by a one vote margin.  Since these cases were not all 5-4 votes there were 15,107 votes in these cases rather than 15,435 (which would be the case if nine Justices voted in each decision).  103 of the 114 sitting Justices across time have voted in these single vote margin decisions which gives us an average of 147 votes for each of the 103 Justices.  This number is top and bottom heavy though and does not accurately depict the extent of most Justices’ participation.

Looking at these 1,705 cases across time there is an increasing number of such decisions.

Just as these decisions are not equally distributed across time, nor are the Justices that decided them.  When we look at the Justices that voted in the most cases decided by a single vote, all the Justices sat on the Vinson through Rehnquist Courts.

Looking at the twenty Justices who had the most votes in such cases, two, Justices Stevens and Brennan voted predominately with the Court’s liberal bloc while Chief Justice Rehnquist was most often associated with a conservative vote.  On one hand, this measure in isolation presents a potential picture of the relative historic power on the Court.  This, however does not disaggregate the Justices that influenced policy through the Court by voting with the majority coalition.  When we separate Justices into the majority and minority coalitions the power dynamic becomes somewhat clearer.

Chief Justice Rehnquist has a margin of thirty-eight more votes in such decisions over the next Justice, Justice White.  There is a large dip of sixty-one more majority votes to the next Justice, Justice Kennedy.

Justice Brennan, however, voted in the Court’s minority more than any other Justice in such decisions.

There is a clear cohesion of liberal Justices at the forefront of the list of Justices in the minority (liberal/conservative coding is supplied by the United States Supreme Court Database).  Justices Brennan, Stevens, Marshall, and Douglas all generally favored the left on issues with significant policy implications.  Somewhat surprisingly, Justices that are typically associated with liberal votes voted conservatively in many of these single vote margin cases and vice-versa.

Although Justices Brennan and Stevens are at the top of the list for Justices with liberal votes in such cases, the next two Justices, Justices White and Rehnquist, are more well known for their conservative voting practices.

The same four Justices make up the Justices with the most conservative votes in such cases.  This split of votes lends credence to the possibility that policy preference may not have been a determinative factor in many of these votes and decisions.

The last three metrics help to differentiate the Justices at the top of this list and provide a clear power leader among the Justices.  Two Justices with much power in each case relative to the other Justices are the majority opinion assigner and author.  Depending on the Justices’ conference vote, the opinion assigner is either the Chief Justice or the senior most associate Justice in the Court’s majority.  This helps explain why four of the five Justices with the most opinion assignments in such cases were Chief Justices.

Chief Justice Roberts makes his way into this chart as one of the top five Justices, but as of the end of the last term Roberts had less than half of the number of assignments as either Chief Justices Burger or Rehnquist.  The meager two decisions last Term decided by one vote do not help Chief Justice Roberts’ overall count very much (there have been no such decisions so far in this 2016 Supreme Court term).  At 62 years of age, Chief Justice Roberts still has the potential to sit on the Court for years and even decades to come.

The last two measures go to the heart of a Justice’s power on the Court as they relate to majority opinion authorship.  The first is the cumulative count of authorship in these single vote margin decisions.

The more conservative Justices seem to have an edge on the top of this list as all three of the Justices with ninety or more of these decisions tended to slant conservatively.  Still Justice White was appointed by a Democratic President in President Kennedy and Justice Kennedy is often a swing vote in close cases and has swayed in both directions.  Finally, looking at self-assignments of such majority opinion one Justice comes out ahead.

Chief Justice (and Associate Justice prior to that) William Rehnquist is the clear leader in terms of this characteristic.  Based on prior theories that opinion assignment can be used as a carrot to move the fifth vote in the assigner’s direction, Chief Justice Rehnquist’s self-assignment count in these cases is even more remarkable and places Chief Justice Rehnquist atop the Justices according to these power measures.

It is perhaps fitting that the most powerful Justice was one of the key votes and was the Chief Justice on the Court that decided Bush v. Gore, the only case to directly resolve a presidential election.  Granted, there are other more elaborate ways of conceiving of Justices’ power.  One could examine specific case issues or look at the length of time certain Justices had a decisive vote in contentious decisions.  Also, Justices that sat on the Court for longer periods of time (especially in the second half of the 20th century) had more opportunities to vote in such cases.  This measure is not relative to the amount of time a Justice sat on the Court or the number of cases they helped decide though.  By treating single vote margin cases equally across time, the Justices’ can be compared by the roles they played when their votes made the biggest difference to case outcomes.

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On Twitter: @AdamSFeldman

Data supplied primarily by the United States Supreme Court Database

Fixed majority votes table: 4/4/17