Significance: Collegiality limits procedural and policy divisiveness within the Court, increases administrative efficiency, allows for a close proximate working environment, and allows the Court to present a united front to the public and the other branches of government, thus increasing its power and prestige.

The chief justice provides leadership in maintaining a collegial working relationship among the justices and their staffs. John Marshall, chief justice from 1801 to 1835, fostered fellowship among the justices by arranging shared accommodations in a single boarding house. Marshall also fostered cooperation among the justices by developing the concept of a single opinion of the Court as a symbol of judicial solidarity. The majority opinion is published as the opinion of the entire Court. Concurring and dissenting opinions are permitted as attachments but are not required and are often forgone to decrease any perception of divisiveness within the Court and to increase the perception of judicial solidarity. Court protocol does not require unanimity but does require deliberation of the cases with mutual respect for the individuality and decision-making ability of each justice, loyalty to the Court as an institution, civil treatment and cordial relations with fellow justices, sharing of opinion writing and other judicial duties, sharing the burden of incapacitated justices in order to shield them from public notice, resolution of internal disputes within the Court and without appeal to outside authorities, and withholding announcement of case decisions until each justice has determined his or her vote on the case. Collegiality encouraged long tenure for members of the Court, unanimity in cases where the institutional integrity of the Court was threatened, and the development of warm personal friendships among the justices. The ongoing spirit of collegiality also helped the Court resist political pressures from the other branches of government, most notably the Depression era Court-packing plan of President Franklin D. Roosevelt. The Court's collegiality was broken only a few times in the Court's history, most notably in the feuds involving Justices Robert H. Jackson, Hugo L. Black, and James C. McReynolds.