WASHINGTON — In a major environmental victory for the Obama administration, the Supreme Court on Tuesday upheld the Environmental Protection Agency’s authority to regulate the smog-causing pollution from coal-fired power plants that wafts across state lines from 27 Midwestern and Appalachian states to the East Coast.

The 6-to-2 ruling upholds a centerpiece of what has become a signature of President Obama’s environmental agenda: a series of new Clean Air Act regulations aimed at cutting pollution from coal-fired power plants. Republicans and the coal industry have criticized the effort as a “war on coal.”

Legal experts said the decision, written by Justice Ruth Bader Ginsburg, signaled that the Obama administration’s efforts to use the Clean Air Act to fight global warming could also withstand legal challenges. The E.P.A. is expected to unveil in June a sweeping new climate change regulation, using the authority of the Clean Air Act to rein in carbon pollution from coal plants.

The regulations covering cross-state air pollution, known as “good neighbor” rules, have pitted Rust Belt and Appalachian states like Ohio and Kentucky against East Coast states like New York and Connecticut.

In its arguments before the court, the E.P.A. said the rules were necessary to protect the health and the environment of downwind states. East Coast states in particular are vulnerable to pollution blown by the prevailing winds of the United States.

In her decision, Justice Ginsburg noted that in reining in interstate pollution, regulators must account for the vagaries of the wind. “Some pollutants stay within upwind states’ borders, the wind carries others to downwind states, and some subset of that group drifts to states without air quality problems,” she wrote, adding a biblical quotation from the Book of John: “The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth.”

The utilities and 15 states on the other side of the issue argued that the rules, as written by the Obama administration’s environmental regulators, gave the E.P.A. too much authority and placed an unfair economic burden on the polluting states.