FEBRUARY 2007

Scales of Justice Tip Slower Than Expected

Illustration by
Michelle Thompson

The magnitude of change is tightly constrained by the median voters’ nearest ideological neighbor.

by Lyn Denend

In the second half of 2005 the U.S. Supreme Court was the subject of intense media scrutiny surrounding the impending retirement of Justice Sandra Day O’Connor and the death of Chief Justice William Rehnquist. Journalists and political analysts alike debated the impact that these two vacancies and the resulting judicial appointments would have on the politics of the court, while the public watched uneasily.

But not Keith Krehbiel, the Edward P. Rust Professor of Political Science. Seeking a more logical, fact-based answer to the question, he initiated a study to determine under what conditions executive appointments to the court would have an immediate bearing on policy. “There was a lot of alarmist press and punditry about how this would tip the court in a radically conservative direction,” Krehbiel recalls. “I had a suspicion that these claims were overstated.”

Krehbiel argues that no single appointment can have a truly profound, immediate effect on the politics of the court because of the complex conditions required to move the median vote by a member of the court to a more conservative or liberal position. While he concurs that appointments have important consequences on public policy in the aggregate and over the long term, Krehbiel maintains that the average appointment opportunity is of limited consequence to short-term policy outcomes.

Applying his expertise in game theory and collective choice, Krehbiel analyzed four decades of Supreme Court appointment data. Central to his study is the idea that within the court, as within any institution that exercises collective choice, there is a median (the voter for whom half the other voters are to his right and the other half are to his left in terms of the conservatism or liberalism of their views). The median acts as a strong gravitational force in decision-making, since no given policy can command majority support without winning the median voter’s support. The court’s median policy is difficult to move, as Krehbiel explains, “because a majority can’t be put together to move it left, and a majority can’t be put together to move it right.”

A presidential appointment can move the median only when specific conditions are met. First, the views of the vacating justice and the president must be on opposite sides of the median; otherwise, any new appointment will serve only to maintain the status quo. Second, the pivotal voter in the Senate also must hold views on the same side of the median as the nominee in order for the nomination to be confirmed.

“Even when both conditions are met, the magnitude of change is tightly constrained by the median voter’s nearest ideological neighbor,” he said. If, for example, a new justice joins the court to the right of the established median, the new median will shift no further than the justice with the voting record closest to the previous median voter—albeit slightly to the right—an incremental move.

As a result, Krehbiel says, “the conditions for a single Supreme Court appointment to be cataclysmic are basically never going to be met.”

The Supreme Court appointment opportunities in 2005 illustrate his point. John Roberts was appointed to replace Rehnquist—resulting in the preservation of the status quo because Rehnquist’s voting record was squarely to the right of the established median and Robert’s ideological views were directionally aligned with Rehnquist, as well as with the president and the Senate.

Keith Krehbiel

O’Connor’s replacement, on the other hand, was slightly more interesting, “because people said, ‘O’Connor is the swing voter, and replacing the swing voter with a conservative will radically tip the court.’” In reality, the effect of the change is likely to be limited, Krehbiel says. “As it turns out, Anthony Kennedy and O’Connor had virtually identical voting records, with Kennedy very slightly more conservative than O’Connor. So, regardless of how conservative her replacement [Samuel Alito] is, it’s only going to move the median a trace.”

Krehbiel acknowledges that the long-term implications of successive appointments by a single political party can be significant. Referencing the 10 uninterrupted appointments to the Supreme Court made by the Republican Party under Presidents Nixon, Ford, Reagan, and Bush Sr., he says: “From 1969 to 1992, a considerable amount of conservative drift occurred because incremental changes added up. But the ideological pendulum swings both ways. So, considered in the broader historical context, the theory suggests that the court’s contribution to public policy eventually will inch back toward more liberal policies.”

How soon might we expect this? Not soon. First, Democrats must win a string of presidential elections. Second, retirements from the court have to occur disproportionately from the conservative wing to create several opportunities for left-of-center presidents to move the median. Third, the Senate must give consent.

The demographics of the present court do not favor a Democratic policy shift, he says. “The three justices under 60—Roberts (52), Alito (56), and Thomas (58)—are among the most conservative, and they can be expected to stick around a long time. Meanwhile, the two oldest justices—Stevens (86) and Ginsberg (73)—are most liberal by most measures. If the seniors leave before the juniors, then a successful Democratic appointee will not move the median at all. If the seniors were somehow to outlast the juniors, a successful Democratic appointee will move the median only slightly—for example, from Kennedy to Breyer.”

Stanford Business

Scales of Justice Tip Slower Than Expected

The magnitude of change is tightly constrained by the median voters’ nearest ideological neighbor.

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