As the justices of the Supreme Court prepare to reconvene for their conference and take the bench for the 2026-27 term, attention will shift toward which new cases will be added to the docket for oral argument and decision. At the heart of this process is the longstanding custom known as the “rule of four.” This unwritten practice allows the Court to hear a case if four justices vote in favor, even if the majority prefers not to.
The rule of four traces its roots to a time when the Supreme Court faced an overwhelming number of cases due to the direct appeal system of the 19th century. The establishment of federal circuit courts in 1891, and later the introduction of the certiorari process in 1925, granted the Supreme Court greater discretion in case selection, reducing its obligatory caseload. Chief Justice William Howard Taft formalized the rule, ensuring that the interests of four justices could suffice to place a case on the docket.
This practice, however, is steeped in a degree of complexity and raises procedural questions. For instance, while the rule of four can lead to certiorari, it does not guarantee action on related emergency measures. Case in point: in 1990, James Edward Smith was executed despite four justices voting to hear his appeal concerning mental competence because a fifth vote was not secured for a stay of execution. To mitigate such occurrences, the Court often employs a “courtesy fifth” vote—an informal practice where a justice supports a stay to honor the four votes for certiorari.
The rule of four is an example of how customs shape the procedural landscape of the Court, sometimes leading to a “dismiss as improvidently granted” (DIG) when procedural flaws are identified post-certiorari. The Court’s commitment to both tradition and collegiality comes to the fore here, where a DIG typically requires six votes, including one from the cohort that initially granted certiorari. Not all practices endure, as seen with the now-dormant “join 3” vote, which allowed a justice to pend their vote contingent on three others.
In the forthcoming months, the Supreme Court is expected to review up to three dozen petitions for certiorari. The interactions between tradition and legal obligation continue to underscore the intricate workings of the nation’s highest judicial body, providing a framework within which justices navigate the complex and often opaque processes of case selection and adjudication. Understanding these nuances lends insight into the deliberative processes that influence pivotal legal decisions.