Final answer:
The Judicial Procedures Reform Bill of 1937, known as Roosevelt's "court-packing scheme", aimed to add up to six new justices to the Supreme Court to create a majority favorable to New Deal programs, but was criticized and never passed. A Supreme Court justice's shift in position averted the need for such measures.
Step-by-step explanation:
The plan that resulted from a series of judicial activism actions and ultimately caused the "switch in time that saved nine" was the Judicial Procedures Reform Bill of 1937. This proposal, commonly referred to as President Franklin D. Roosevelt's "court-packing scheme", aimed to reorganize the judiciary by allowing the president to appoint an additional Supreme Court justice for every justice over seventy who refused to retire, potentially adding up to six new justices. The motive behind this plan was to obtain a Supreme Court more favorable to Roosevelt's New Deal programs, which had been struck down by the court as unconstitutional. The bill was met with great criticism and never passed; however, the mere debate seemed to influence the Supreme Court justices' positions, as one justice began to side with Roosevelt on key issues, which avoided the need for the controversial plan and preserved the traditional number of nine justices on the bench.