terminate the position of any existing Justice; the law provided that, whenever the next Justice left the Court, the vacancy would not be filled.) In 1802, the new Democratic Republican Congress then repealed that 1801 law and restored the Court to six members.[4] In 1807, Congress added one Justice to increase the size to seven members,[5] and in 1837, Congress expanded the size to nine members.[6]
Each reform seems to have been motivated by a mix of institutional and political concerns. During the early years of the Court, each Justice had two duties: both to sit on the Supreme Court and to serve as a judge on a lower federal court (a practice known as “circuit riding”).[7] In 1789, Congress created a six-member Supreme Court to serve the existing federal circuits. Over the next several decades, as the country grew in size, it became clear that more judges were needed, particularly in newly admitted states such as Kentucky, Tennessee, and Ohio, and (later) Louisiana, Illinois, Alabama, and Missouri.[8] In 1807, Congress added a seventh circuit, and in 1837, an eighth and a ninth circuit. Each time, Congress expanded the size of the Supreme Court accordingly.[9] These expansions served an institutional purpose: providing sufficient judicial machinery for a growing nation. But each expansion also served the interests of a political party. In 1807, the Democratic Republicans controlled Congress and trusted their party leader—President Jefferson—to appoint the seventh Justice. In 1837, the Democrats who controlled Congress had similar confidence in their party leader President Andrew Jackson.[10] The new courts created also ensured that a majority of circuits would cover slaveholding territory and therefore that a majority of Justices would be friendly to slavery.[11]
The reforms in 1801 and 1802 can also be explained by a mix of institutional and political concerns. In 1801, the Federalist Congress temporarily ended circuit riding,[12] and so its reduction of the Court to five Justices could have been justified by the fact that the Court could now function effectively with only five members. But the reduction in size was also likely attributable to the Federalists’ desire to prevent their incoming political rival—President-elect Jefferson—from filling a Supreme Court vacancy.[13] When the Democratic Republicans repealed the 1801 law and returned the Court to six Justices, they also re-established circuit riding and thus the link between the number of Justices and the number of circuits.[14] But their re-expansion of the Court also coincided with their political interest in giving President Jefferson an opportunity to shape the future of the Court.
In the 1860s, Congress made several changes to the size of the Supreme Court in fairly short order. These changes were not tied as closely to the number of lower circuit courts and are often said to have had a primarily political motivation.[15] Many lawmakers were deeply skeptical of the Court after its 1857 decision in Dred Scott v. Sanford, which held that African-
