What moves the Supreme Court's 'swing' justices?

November 1, 2013 by H. Roger Segelken

Whenever the U.S. Supreme Court hands down a 5-4 decision, the pivotal "swing" vote must be cast by the "median" justice (midway, ideologically, between four more liberal justices and four more conservative), right?

Not necessarily, according to two who reviewed hundreds of Supreme Court decisions between 1953 and 2009.

In a study published in the October issue of the Journal of Politics (75: 4), Cornell's Peter K. Enns, assistant professor of government, and his co-author report that in a substantial number of cases, the justice casting the pivotal swing vote was not the ideological median (think Anthony Kennedy in recent years). Furthermore, they report, – even in the Courts' most closely divided cases – has a more profound effect than might care to admit.

"Whether the swing justice represents the moderate center of the court or a more extreme ideological position, this justice's correspond more closely with public opinion and less with personal preferences than do the other justices' votes," says Enns, who wrote "The Swing Justice" with Patrick C. Wohlfarth of University of Maryland, College Park.

"We were particularly interested in cases where the most ideologically extreme justices sometimes cast the pivotal vote against their ideological predisposition," Enns said. "What makes a justice who typically votes in an ideological manner 'leapfrog' a more moderate justice and cast a surprising vote?"

Until Supreme Court justices retire and write memoirs, scholars like Enns and Wohlfarth can only make educated guesses – backed by historical analyses of hundreds of Supreme Court decisions – and they advance two hypotheses for surprising swing votes:

Justices sometimes are moved to vote, in what Enns and Wohlfarth call a "nonattitudinal" way, by case-specific considerations such as the legal facts of the case, oral arguments or the solicitor general's amicus briefs. And sometimes justices may be uniquely influenced by the "details and context of the case," they write. Public opinion is one detail in that context. In other words, Supreme Court justices are "human actors," and swing justices might be the most human of the bunch.

While that news might encourage the sign-carrying public to congregate on the Supreme Court plaza (in defiance of the high court's ban on demonstrations there), leaders of other federal government branches – like the U.S. Congress – should also ponder the dynamics of swing voting, the political scientists suggest.

"If we want to understand who influences policy outputs in Congress," they conclude in their paper, "we cannot only look at representative behavior, on average. We must also understand the potentially unique behavior of pivotal swing members."

Explore further: Researchers find appointed justices outperform elected counterparts

Related Stories

Recommended for you

The culinary habits of the Stonehenge builders

October 13, 2015

A team of archaeologists at the University of York have revealed new insights into cuisine choices and eating habits at Durrington Walls – a Late Neolithic monument and settlement site thought to be the residence for the ...

Ancient genome from Africa sequenced for the first time

October 8, 2015

The first ancient human genome from Africa to be sequenced has revealed that a wave of migration back into Africa from Western Eurasia around 3,000 years ago was up to twice as significant as previously thought, and affected ...

Mexican site yields new details of sacrifice of Spaniards

October 9, 2015

It was one of the worst defeats in one of history's most dramatic conquests: Only a year after Hernan Cortes landed in Mexico, hundreds of people in a Spanish-led convey were captured, sacrificed and apparently eaten.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.