The Conservative Bias of Tightly Split Opinions

Abstract

This paper documents a paradoxical phenomenon in tightly split opinions of the United States Supreme Court. They exhibit a conservative bias. This bias of 5–4 opinions from 1946 to 2018 has remained mostly steady at about 58% conservative. Other splits of the United States Supreme Court do not exhibit similar consistency, except 9–0 splits. Those have a liberal bias, but only until the 1975 term. Forces consistent with the data are offered as avenues for further research: (a) pliant conservatism to 1975 and firm conservatism from 1976 in the justices; (b) nation-shaping liberal decisions that attracted unanimity and repelled tight splits to 1975; (c) liberal justices not voting for certiorari in some disputes after 1976; liberal litigants (d) switching from firm to conciliatory attitudes in 1976; and (e) reducing their test case litigation in 1972.