The Paradox of Self-Amendment: A Study of Law, Logic, Omnipotence, and Change Peter Suber, Philosophy Department, Earlham College
http://www.earlham.edu/~peters/writing/psa/index.htm
Basically some of Russell and Godel's work applied to legal change. There's also a great piece in "Is Capitalism Sustainable" [no] on Thomas Blanke's and Ulrich Preuss' ideas on an "ecologically sound constitutional theory" that looks at the German Constitution.
"the earth belongs in usufruct to the living: that the dead have neither powers nor rights over it...no society can make a perpetual constitution or even a perpetual law...." [Thomas Jefferson]
Ian