In a major win for the Obama administration's climate pollution policy, the US Court of Appeals for the District of Columbia Circuit ruled unanimously on Tuesday that the Environmental Protection Agency had lawfully determined that greenhouse-gas emissions pose a danger to public health and welfare.

The appeals court's decision on four major EPA initiatives to regulate carbon emissions was a clear legal victory for the Obama White House and a setback for some industry groups and states including Texas.

It was a big win as well for embattled EPA Administrator Lisa Jackson, whose controversial "endangerment finding" for greenhouse-gas emissions kicked off the legal battle royale in December 2009. Her finding followed the US Supreme Court's 2007 Massachusetts v. EPA ruling, in which the court found that carbon emissions could potentially be regulated under the federal Clean Air Act.

After that first finding, the EPA proceeded to issue other regulations to curtail carbon emissions. First came the Tailpipe Rule, in 2010, that sets carbon emission standards for cars and light trucks. With its debut, carbon emissions officially became a regulated pollutant under the Clean Air Act.