During the Civil War, the absence of southern Democrats from Congress presented the Republican Party with an opportunity to reduce southern influence in the federal government. One particular target of this initiative was the Supreme Court. By longstanding custom, the president appointed justices residing in the circuit to which they would be assigned for duty on the circuit courts. When Congress reorganized the judicial circuits in order to accommodate six new states, it reduced the number of circuits composed entirely of slave states from five to three. As a result, Abraham Lincoln was able, without ignoring custom, to appoint David Davis of Illinois and Samuel Miller of Iowa to the Supreme Court to serve in the Eighth and Ninth Circuits, respectively. Both circuits had been composed of slave states prior to the 1862 statute and were then altered to consist primarily of northern states. Congress further limited southern influence on the judiciary in 1866, when it reorganized the circuits again and provided for a gradual reduction in the number of authorized seats on the Supreme Court.
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