Twenty years ago, I directed a master's thesis on the evolving structure, strategies, and tactics of the conservative Christian 'creationist movement' through the lens of the battle to control textbook content. The thesis was quite good, a tribute to the smarts and hard work of the candidate more than to any unusual gifts on my part as advisor.
The big whack of the textbook market controlled by Texas (then as now), and the Lone Star State's receptiveness to culture-war rhetoric of the era, made the Texas public school system's textbook selection process a critical leverage point for conservatives.
The thesis writer uncovered one odd little wrinkle: When the State Board of Education committee charged with textbook selection decisions heard testimony about any particular book, it was their practice only to allow testimony against whatever book was currently in adoption, not in support of it.
This had the predictable effect of creating a cottage industry for disciplined citizens who regularly appeared at the hearings to expose supposed liberal/secular bias in textbooks currently in use (which, at the time, meant approving references to the theory of evolution). No testimony in support of the book in question would be heard--and since the creationist textbooks were not under review, no discussion of their shortcomings was in order. Creationism wasn't, as a result, introduced into most textbooks, but the one-sided process did help push major publishers to begin simply watering down or omitting discussion of anything to do with the origin and differentiation of species.
("Half a loaf," indeed. The parallels to the August health care town halls and their aftermath are pretty hard to ignore. But I digress.)
I've been trying--without success--to find out if that negative-comments-only rule is still part of the textbook selection process in Texas today. Does anyone know?