Can Unilateral Carbon Measures Be Consistent with WTO Rules?

My good friends over at the law firm Sidley Austin have done an analysis of whether certain cap-and-trade greenhouse gas legislation under consideration in the U.S. is consistent with WTO rules.  They argue that unilateral legislation can be written in a way that complies with WTO rules, and that the specific proposal they analyze is WTO-consistent.  See Appendix A of the following document for all the details:  http://www.finance.senate.gov/hearings/testimony/2008test/021408abtest.pdf