In The Executive Unbound, Adrian Vermeule and I argued that the Madisonian system of separation of powers has collapsed, and that the executive is mainly constrained by politics rather than law. The Obama administration has produced striking new examples–almost natural experiments, where it started by seeking a law from Congress then gave up and implemented the policy through executive fiat. First was the Dream Act, which would have legalized certain younger undocumented migrants. Congress refused to pass it, and Obama implemented it anyway by ordering ICE to comply with the rules that were never enacted.
And now it is climate. From the news sources I see, the EPA regulations to be announced Monday create the same kind of cap-and-trade system envisioned by the Waxman-Markey bill, which was also not enacted by Congress. The EPA regulations do not encompass as wide a range of pollution sources as the bill did, but the legal authority behind them should give EPA the power to issue additional regulations that do just that.