whether, when, and how the Environmental Protection Agency (EPA) might use its existing organic Clean Air Act (CAA) authority to create a market-based carbon trading system have become among the most vigorously debated issues among climate observers in Washington. Businesses and parties that have hedged investments in anticipation of a mandatory cap-and-trade regime are anxiously dissecting CAA provisions and a small line of cases in an effort to uncover authority for EPA to mimic what Congress has proposed, but has been unable to enact.