The Tenth Circuit upheld on constitutional grounds Colorado's mandate that 20% of the electricity that generators sell to Colorado consumers come from renewable sources. A conservative energy group claimed that the renewable energy standard will harm out-of-state coal producers in violation of the C...

The D.C. Circuit upheld an EPA regulation that requires automobile manufacturers to use "commercially available" fuel when testing the emissions of new vehicles under the CAA. Several producers of E30, a fuel that contains 30% ethanol, argued that a fuel shouldn't have to be commercially available i...