The U.S. Supreme Court handed President Barack Obama a victory on Tuesday by upholding a federal environmental regulation requiring some states to limit pollution that contributes to unhealthy air in neighboring states.

By a 6-2 vote, the court said the U.S. Environmental Protection Agency acted reasonably in requiring 28 states to reduce emissions from coal-fired power plants of sulfur dioxide and nitrogen oxides, which can lead to soot and smog.

Writing for the majority, Justice Ruth Bader Ginsburg called the EPA rule a cost-effective way to allocate responsibility for emission reductions among upwind states, and that the EPA need not consider each state's proportionate responsibility for the emissions in question.