One can sympathize with the terrible choices the administration was faced with after the terrorist attacks of September 11, 2001.
I, however, believe that the administration went to far in their, arguably, knee-jerk reaction (perhaps it was a well planned reaction?).  I also get the impression that much of the stone-walling now is, in great part, due to the fear that the administration has that it will be prosecuted for some of the positions and policies they have taken and made.
The chapter also indicates that members of the administration had clear policy objectives which may have been well served by the terror attack. In the case of Cheney it appears that he always wanted to dramatically expand the power of the Executive just as it is becoming apparent that the decision to declare war on Iraq was a preferred policy of many in the administration prior to the terror attacks.
It is hard to know, definitavely, whether the administration used the terror attacks to press for the policies they wanted or whether the policies they wanted happened to be the prescription for the security issues the United States faces and has always faced.  I am getting the impression that it is the former.
The United States has a history of terrorism (school and work shootings, abortion bombings, Waco, Oklahoma, lynchings) and it is interesting that none of the dramatic measures instituted by the Bush administration were needed, or in place, prior to September 11, 2001. 
We managed just fine using our Constitution for over two hundred years and I am wondering why it is, all of a sudden, a burden to follow the law.