Explainers
Key concepts for interpreting Supreme Court decisions and vote data.
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A 5-4 decision is the narrowest possible majority on a nine-member Court: five justices one way, four in dissent. These cases are often the most contentious and consequential. Since 1946, roughly 20% of decided cases have been 5-4 splits.
The Supreme Court Database (SCDB), maintained at Washington University in St. Louis, is the most widely used academic dataset of Court decisions. It encodes every orally argued case since 1946 with over 200 variables. This site uses SCDB as its primary structured data source.
SCDB classifies cases into 14 issue areas such as Criminal Procedure, Civil Rights, First Amendment, and Economic Activity. Vote splits (9-0, 7-2, 5-4) describe how many justices joined the majority versus the dissent.
SCDB codes each decision as "conservative," "liberal," or "unspecifiable" per conventional legal-political categories. These labels reflect scholarly coding conventions — not the justices’ self-identification — and are most useful for longitudinal trend analysis.
The Roberts Court (2005–present) decides fewer cases per term than earlier eras — roughly 60–70, versus 130+ under the Burger Court — but a larger share involve closely divided votes.
The petitioner asks the Court to review a lower-court decision; the respondent defends it. Historically, petitioners win more often — the Court tends to grant review when it suspects error below.