The United States Supreme Court held,
in Massachusetts v. EPA, that the EPA has the authority to regulate
CO2.  It was a 5-4 decision, with Kennedy signing on with the
“liberal wing” of the Court.

This case was about standing that
turned into a case about the Court thinking it was an expert on climate
science.  It also is a shocking display of the Court deciding that
it knows better than a government agency on regulatory issues. 
There is significant deference given to agencies, but for some reason,
the Court decided to weigh in on a matter that properly was a question
for the other branches of government.  The dissent argued, as I
expected, that the case was about standing.

The result is not
surprising–it was going to be a 5-4 decision.  The only drama was
whether Kennedy would understand that there was no standing (he
obviously didn’t).  This is just another example of judicial
activism–the Court deciding an issue that it had no business deciding
because it wants to be a policymaking body, not a judicial body.