For decades now, scholars have debated whether the Supreme Court takes into account the preferences and likely action of the contemporaneous Congress when it interprets federal statutes. Forcefully represented by Jeffrey A. Segal & Harold J. Spaeth (2002), attitudinalists argue that the Justices vote on the basis of their ideological attitudes vis-à-vis the facts of cases. Period. As they famously declared, “Rehnquist voted the way he does because he was extremely conservative; Marshall voted the way he did because he was extremely liberal.” Congressional preferences have little role to play in this analysis (and besides, as Segal  demonstrated, the legislative process almost never constrains the Justices from voting sincerely). Spiller (with various co-authors), Knight, and I have taken exception to this account (e.g., Bergara, Richman & Spiller 2003; Gely & Spiller 1990; Spiller & Gely 1992; Epstein & Knight 1998). To us, policy-seeking Justices must engage in “dynamic” statutory interpretation (Eskridge 1991). If they do not, they run the risk of Congress overriding their decisions—in which case their least favored interpretation may become law.
Debates over the nature of statutory interpretation will inevitably continue. Where less controversy exists is over constitutional interpretation. Many scholars argue that the Supreme Court need not pay too much attention to Congress when it interprets the Constitution because (1) Congress can’t override its constitutional decisions by a simple majority and (2) other weapons to attack the Court (e.g., jurisdiction stripping, impeachment, budget reductions) are almost never deployed. But ”many” is not all. Meernik & Ignagni (1997), for example, partially refute (1). Their data show that while the Court may say that Congress can’t overturn constitutional decisions, Congress isn’t listening. Between 1954 and 1990, it overturned about forty constitutional decisions by statute. As for (2), Knight, Martin, and I (2001) have made the case that Congress almost never needs to punish the Court precisely because the Justices attend to congressional preferences and interpret accordingly.
That Segal would attempt to assess the role of Congress in the Court’s interpretation of the Constitution was inevitable; his fingerprints are all over the study of judicial behavior. That he (with his co-authors) would be the first to offer systematic evidence of the constraints Congress imposes on the Court, well, that’s downright delicious–especially to those of us–many close friends!–who have long debated the matter with him.
Interestingly, though, according to the authors, the real constraint does not come from (1). Their analysis suggests that the Court is not especially worried about Congress overriding its constitutional decisions. But the data do show that the Court responds to (2)—the possibility of institutional retaliation by Congress. As the ideological distance between the median Justice and the house of Congress closest to her increases, the probability that the Court will invalidate a federal law declines significantly and substantially. No wonder Congress rarely strips the Court’s jurisdiction, reduces its budget, impeaches its members, or otherwise seeks to undermine its institutional legitimacy. The Justices sense danger and retreat.
Characterized in this way, the results are not inconsistent with Segal’s earlier work on interpreting federal laws: in neither the statutory nor the constitutional context do the Justices seem especially worried about congressional overrides or modifications of particular decisions. On the other hand, this latest effort should raise serious concerns about the sufficiency of any account that paints the Justices as unconstrained ideological voters.