in 1807, congress passed the seventh circuit act (), which added a sixth associate justice to the supreme court. two more seats were added in 1837, as a result of the eighth and ninth circuits act (); one of these (seat 7 below) was later abolished as a result of the judicial circuits act of 1866. the supreme court reached its peak size in 1863, when the tenth circuit act () became law, and a tenth justice joined the court. after fluctuating from nine to ten to eight members over a six-year period, the size of the court was restored to nine members through the circuit judges act of 1869 (), a broad reconstruction era reorganization of the federal courts. this act remains (as of the 115th congress) the governing law regarding the number of seats on the court.