The Supreme Court had three questions before it: Do states have the right to sue the EPA to challenge its decision? Does the Clean Air Act give EPA the authority to regulate tailpipe emissions of greenhouse gases? Does EPA have the discretion not to regulate those emissions?
The Court said 'yes' to the first two questions and, on the third, it ordered EPA to re-evaluate its contention it has the discretion not to regulate tailpipe emissions.
The Court said the agency has so far provided a "laundry list'" of reasons that include foreign policy considerations and added that the EPA must tie its rationale more closely to the Clean Air Act.
The political climate has changed dramatically over the issue of global warming since the court agreed last year to hear the case -- the Supreme Court's first on the subject.
In November of 2006, Democrats took control of Congress and pledged to make global warming a national issue.
In February, the world's leading climate scientists reported global warming is "very likely" caused by man and is so severe that it will "continue for centuries."
An interesting development in the politics of climate change is how the issue of global warming is playing out in the 2008 presidential campaign.
"Virtually all of the frontrunners for the 2008 presidential bid are significantly stronger on this issue (than the Bush administration)," said Chris Miller of Greenpeace, pointing to '08 candidates Sen. Hillary Clinton, D-N.Y., Sen. Barack Obama, D-Ill., and Sen, John McCain, R.Ariz., who all advocate capping greenhouse gas emissions.
But perhaps one of the biggest political players in the climate change arena is former Vice President Al Gore.
His Academy Award-winning documentary, "An Inconvenient Truth", which makes the case for prompt action on climate change, has gained widespread attention and applause, not to mention giving Gore a microphone to the world during the Oscars.
Standing alongside David Guggenheim, director of the Gore-inspired documentary, on stage, Gore proclaimed, "My fellow Americans, people all over the world -- we need to solve the climate crisis. It's not a political issue. It's a moral issue. We have everything we need to get started with the possible exception of the will to act. That's a renewable resource. Let's renew it."
The former Vice President turned environmental activist also recently testified before both the House and Senate on the issue of global climate change, spurring rumors of another presidential bid, all of which have been downplayed but not entirely rejected by Gore.
ABC News' Jan Crawford Greenburg, Ariane DeVogue, and Dennis Powell contributed to this report.