Court Packers

"When the court overreaches, the Constitution provides checks and balances. In 1805, after persistent political activity by Justice Samuel Chase, Congress responded with its power of impeachment. Chase was acquitted, but never again did he step across the line to mingle law and politics. After the Civil War, when a Republican Congress feared the court might tamper with Reconstruction in the South, it removed those questions from the court’s appellate jurisdiction.
"But the method most frequently employed to bring the court to heel has been increasing or decreasing its membership. The size of the Supreme Court is not fixed by the Constitution. It is determined by Congress."

In The New York Times, Jean Edward Smith traces the fluctuating numbers of Supreme Court justices.