A wisp of hope drifts around the murk of energy legislation under development in the US. It’s a federal tax system on the verge of self-destruction.As the first session of the 110th Congress approaches its end, Democratic leaders are desperate to pass an energy bill. Because reconciliation of disparate measures passed by the House and Senate requires a political fight no one seems to want, the House leadership has been circulating revised legislation they hope can pass.The discussion draft first jettisoned then reimposed tax increases on the oil and gas industry. But it retained a martial approach to energy markets, with toughened fuel-economy standards for new motor vehicles and ag...