Global warming and the U.S. Constitution A conference organised by the University of Arizona Law School (Feb. 11, 2008) discusses how the U.S. Constitution restrains states from enacting global warming legislation. The principles of statutory interpretation and the relatively obscure constitutional concept of preemption are at the heart of these discussions. Not for the fainthearted. Part 1, (WMP or Flash, 57 min. no transcript) is here. Part 2 (40 min) with Justice Stephen Breyer is here.