Does Birth Order Dictate Supreme Court Justices' Decisions?

Members of the Supreme Court await U.S. President Barack Obama's State of the Union address on January 12. Justice Ruth Bader Ginsburg (center), who was raised as an only child after her older sister died, tends to vote liberal. By contrast, research shows that a justice who was a first or only child is likely to be more conservative. Jonathan Ernst/Reuters

This article first appeared on the Supreme Court of the United States blog.

In a recent Law & Society Review article, "Birth Order, Preferences, and Norms on the U.S. Supreme Court," Kevin McGuire assesses the influence of childhood birth order on the justices' later ideological preferences and approaches to jurisprudence.

Looking back at the past 55 justices (1900-2010), McGuire begins by finding a correlation between their political ideologies and birth order. His second finding, perhaps of greater interest to readers, is that birth order offers an explanation for the willingness of different justices to use their judicial authority to effect policy change.

A justice who was a first or only child is more likely than other justices to hold conservative political ideologies and is less willing to strike down legislation, even when disagreeing with the law. The reverse is true of justices who were a middle or youngest child; these justices tend to hold liberal political ideologies and more readily invoke judicial review.

McGuire draws from research in the field of evolutionary psychology, which investigates how individuals make psychological adaptations to their environments, including the family especially.

First-born children tend to conform to expected norms of behavior to win parental approval. This socialization results in a pattern in which, as adults, they conscientiously respect authority and attach importance to established rules.

By contrast, later-born children seek to distinguish themselves and gain parental attention by generally rejecting the rules and authority structures to which older siblings adhere. As adults, later-born children exhibit more intellectual innovation and less interest in the maintenance of the status quo.

In keeping with the expectations of birth-order socialization, McGuire finds a linkage between the political preferences of members of the court and their birth order, with first-born justices more conservative and later-born justices more liberal, even accounting for other factors that contribute to an adult's political ideology.

During nearly all of the Warren Court, for example, there was no first-born justice. By contrast, the more conservative Rehnquist and Roberts courts have included only modest numbers of later-born justices.

What is perhaps more interesting is that birth-order socialization further suggests that first-born justices (even those who hold liberal views) should place greater weight on rules of jurisprudence and institutional norms and should less willingly oppose popular decision-makers.

Indeed, McGuire's survey of past decisions, controlling for the ideological sway of the justices and the rulings, finds that first-born justices are "relatively hesitant" to overturn elected officials or defy existing precedent, whereas later-born justices display a "marked readiness to invoke the power of judicial review." The presence of numerous amicus briefs, especially one from the solicitor general, heightens this effect.

Two quotations from famous justices illustrate in their own words this dynamic. Justice Oliver Wendell Holmes, the first child in his family, expresses the deference to precedent one would expect from an oldest child:

I sometimes tell students that the law schools pursue an inspirational combined with a logical method, that is, the postulates are taken for granted upon authority without inquiry into their worth, and then logic is used as the only tool to develop the results....

I do not expect or think it desirable that the judges should undertake to renovate the law. That is not their province...and because I believe that the claim of our especial code to respect is simply that it exists...and not that it represents an eternal principle, I am slow to consent to overruling a precedent.

Justice William Douglas, who was not the eldest child in his family, does not share this same deference:

It is overemphasize stare decisis as a principle in the lives of men.... The place of stare decisis in constitutional law is even more tenuous. A judge looking at a constitutional decision may have compulsions to revere past history and accept what was once written.

But he remembers above all else that it is the Constitution that he swore to support and defend, not the gloss which his predecessors may have put on it. So he comes to formulate his own views, rejecting some earlier ones as false and embracing others.

He cannot do otherwise unless he lets men long dead and unaware of the problems of the age in which he lives do his thinking for him.

On the current court, Justices Antonin Scalia, Clarence Thomas, Ruth Bader Ginsburg, Stephen Breyer, Samuel Alito and Sonia Sotomayor are all effectively first or only children. (Ginsburg's older sister died when she was 6, and Thomas was raised separately from his older brother from the age of 7.)

Chief Justice John Roberts and Justices Anthony Kennedy and Elena Kagan are middle children. With the retirement of Justice John Paul Stevens, no youngest child serves on the court.

Given that this lineup, with its mix of first-born and later-born children, is set for the time being, I am not sure what birth-order findings might have to say about specific cases this term. But they add insight and a human dimension to the individuals sitting on the bench.

Andrew Hamm is manager of the SCOTUS blog.