This book considers the political and constitutional consequences of Vieth v. Jubelirer (2004), where the Supreme Court held that partisan gerrymandering challenges could no longer be adjudicated by the courts. Through a rigorous scientific analysis of US House district maps, the authors argue that partisan bias increased dramatically in the 2010 redistricting round after the Vieth decision, both at the national and state level. From a constitutional perspective, unrestrained partisan gerrymandering poses a critical threat to a central pillar of American democracy, popular sovereignty. State legislatures now effectively determine the political composition of the US House. The book answers the Court’s challenge to find a new standard for gerrymandering that is both constitutionally grounded and legally manageable. It argues that the scientifically rigorous partisan symmetry measure is an appropriate legal standard for partisan gerrymandering, as it logically implies the constitutional right to individual equality and can be practically applied.