This publication includes cases that depict the Supreme Court’s broad deference to the political branches in the immigration realm, the so-called “plenary power doctrine.” Selected cases are presented in chronological order, beginning with the Supreme Court’s consideration of the Chinese Exclusion Acts of the 1880s and 1890s. The book then examines how the Cold War tested the constitutional limits of the government’s plenary power over immigration, and how “phantom constitutional norms” were later used to defeat the government’s broadest claims. Other cases explore the immigration enforcement system and the difficulty of balancing the demands of enforcement against other societal goals. David A. Martin is the Warner-Booker Distinguished Professor of International Law at the University of Virginia. Peter H. Schuck is the Simeon E. Baldwin Professor of Law at Yale Law School.