Several twentieth-century presidents have attempted to greatly expand the power of the presidency. Theodore Roosevelt, for instance, claimed that the president was permitted to do whatever was not explicitly prohibited by the law—in direct contrast to his immediate successor, William Howard Taft. Franklin Delano Roosevelt held considerable power during the Great Depression. Congress had granted Franklin Roosevelt sweeping authority; in Panama Refining v. Ryan, the Court for the first time struck down a Congressional delegation of power as violative of the doctrine of separation of powers. The aforementioned Schechter Poultry Corp. v. United States, another separation of powers case, was also decided during Franklin Roosevelt's presidency. In response to many unfavorable Supreme Court decisions, Roosevelt introduced a "Court Packing" plan, under which more seats would be added to the Supreme Court for the president to fill. Such a plan (which was defeated in Congress) would have seriously undermined the judiciary's independence and power.