Drift, draft, or drag: How U.S. supreme court justices react to new members

Using the Martin-Quinn ideology scores, we show that U.S. Supreme Court justices strategically respond to Supreme Court membership change. At the aggregate level, the Court moves to counterbalance the ideological change brought about by a new justice. The behavior is most prevalent in 1938-48 (a period of “constrained liberalism”) and 1975-95 (a period of “constrained conservatism”). At the individual level, membership change in the conservative direction leads to a greater response from liberal justices, while a change in the liberal direction leads to a greater response from the conservative justices. One possible implication of our results is that the prevalence of this counterbalancing reaction to membership change may have a stabilizing effect on the aggregate ideology of the Supreme Court.