A Stealth O'Connor or Souter After All?

[truger at law.upenn.edu]

To return to an issue from a few posts ago, namely whether Souter and 
other Justices have "drifted" during their careers on the Court, we can 
learn something from the attitudinal ideal point research that 
political scientists have done for individual Justices in each Term 
going back the past several decades.  The best models, like that of 
Andrew Martin and Kevin Quinn, attempt to adjust for changing case 
stimuli and other factors to achieve more consistency across time.  
Even as a skeptic of the attitudinal model as a complete causal 
explanation of judges' behavior, I find this body of research useful 
for comparative purposes--in assessing shifts in a Justice's voting 
behavior relative to other Justices on the same court, and also for 
assessing longitudinal "drift" in the course of that Justice's own 
career on the Court.

Much of what this historical ideal point research suggests is already 
well recognized by everyone -- e.g., that Blackmun was a big drifter in 
a liberal direction, as was Souter to a less dramatic extent.  Other 
findings, oversimplified for brevity, are:

1.  About 30 to 40 percent of Justices in the past 50 years who've 
served more than a decade exhibit some significant linear shift in 
their attitudinal ideal point.  About the same number are quite stable 
over time; the remaining handful exhibit some variation but in a 
nonlinear fashion.

2.  Often these shifts are imperceptible because a justice started out 
at one side of the Court and simply got more extreme in his voting 
behavior with time (this would apply to Douglas, Marshall, and Scalia 
for example). 

3.  More of the biggest drifters have gone in a liberal than 
conservative direction, but drift is not always liberal: conservative 
drifters include Black, Frankfurter, and White.

4.  Some marked shifts appear motivated by strategic rather than 
attitudinal reasons.  For instance, Rehnquist's voting ideal point 
moved markedly toward the center of the Court when he become Chief, a 
move explainable on several strategic grounds.  More puzzling perhaps 
is Stevens, whose votes became demonstrably more "liberal" just after 
Brennan and Marshall retired--that is, as soon as he became the outlier 
on that end of the attitudinal spectrum on the Court.  This could 
represent a sincere change in ideology, but I imagine something else is 
involved, perhaps a perceived need to occasionally give voice to an 
alternative view than the 8 other current Justices, and one formerly 
expressed by his former colleagues.   


The real question, of course, which no one has answered, is whether 
there are observable characteristics at the time of nomination that 
correlate with a judge's tendency to drift on the bench.  My sense, and 
that of others who have looked at this, is that such criteria do not 
exist in a form we can readily recognize and measure.  So all of this 
still leaves us guessing about what kind of justice Roberts will be.

If you're interested in citations to this research, or in a draft paper 
I wrote on this phenomenon a few months ago, send a message off list 
and I'll send them along.

Best,

Ted 

Theodore Ruger
Assistant Professor
University of Pennsylvania Law School
3400 Chestnut Street
Philadelphia, PA 19104
(215) 573-6018
truger at law.upenn.edu