After the terrorist attacks of September 11, 2001, the U.S. Immigration and Naturalization Service (INS) came under fire for the role that it unwittingly played in allowing foreign terrorists to enter the country. As the arm of the Justice Department charged with overseeing immigration policy, the INS had the dual responsibility of preventing unlawful immigration and of awarding citizenship to legal immigrants. Many critics maintain that the agency’s lenient standards and lax enforcement policies enabled the September 11 terrorists to carry out their plans. For example, each of the nineteen hijackers had been granted visas (temporary permits to travel) from the U.S. State Department, but three of them violated the terms of their visas without attracting the attention of the INS. One of the hijackers, Hani Hanjour, was granted a student visa to study English but never attended...