In the years before World War II, Franklin Roosevelt’s fiercest, most unyielding opponent was neither a foreign power nor “fear itself.” It was the U.S. Supreme Court.

When the Court’s conservative majority knocked down the pillars of the New Deal, one after another, democracy itself stood on trial. If Roosevelt was going to have any hope of changing America, he would have to find a way to overcome the Court. In 1937, he struck back with an audacious plan to pack the Court with liberals. The ensuing fight was a partisan firestorm. The battle dealt Roosevelt the biggest setback of his political life and forever split the Democratic party. But it also brought the Court and Constitution into the twentieth century.

Supreme Power unfolds like a thriller. It reveals why understanding the Court fight is essential to understanding the presidency and legacy of FDR — and to understanding America in our own, contentious times.