David C. Bennion, with whom Free Migration Project was on brief, for petitioner. Lindsay Corliss, Trial Attorney, Office of Immigration Litigation, Civil Division, United States Department of Justice, with whom Joseph H. Hunt, Assistant Attorney General, John S. Hogan, Assistant Director, Office of Immigration Litigation, Daniel E. Goldman, Senior Litigation Counsel, Office of Immigration Litigation, and Andrea N. Gevas, Trial Attorney, Office of Immigration Litigation, were on brief, for respondent.