Not much of a victory considering that the high court reaffirmed the regulatory authority of the EPA to set rules on carbon emissions:

The Supreme Court rejected a climate change lawsuit against major power companies Monday, ruling that the Environmental Protection Agency, not the courts, should impose curbs on greenhouse gas emissions.

The unanimous decision immediately raises the stakes in the ongoing battle over EPA's pending greenhouse gas rules by stymieing direct court cases against power companies over climate change.

The Supreme Court opinion is a victory for power companies and for the Obama administration, which has called on the high court to give deference to EPA's pending climate regulations.

[...]

"The critical point is that Congress delegated to EPA the decision whether and how to regulate carbon-dioxide emissions from power plants; the delegation displaces federal common law," the decision states.

The ruling builds on a 2007 decision in Massachusetts v. EPA in which the Supreme Court said that greenhouse-gas emissions could be regulated under the Clean Air Act if EPA found they endanger public health and welfare. EPA later made such a finding and has begun phasing in a series of rules aimed at ratcheting down the emissions.

Congress still might overrule the EPA, but without Obama's signature, it is not likely to become law. It is classic bureaucratic overreach at the expense of the legislative branch and the Supreme Court is making a political statement by reaffirming the EPA's mandate to regulate CO2.