“By the seventh year of the Bush-Cheney presidency, Bush had attached signing statements to about 150 bills enacted since he took office, challenging the constitutionality of well over 1,100 separate sections in the legislation. By contrast, all previous presidents in American history combined had used signing statements to challenge the constitutionality of about 600 sections of bills, according to historical data compiled by Christopher Kelley, a Miami University of Ohio political science professor who was one of the first to study signing statements.”