A Supreme Court ruling this week dealing with a provision of the Clean Air Act that had been in dispute since the days of the Bush administration provided a major victory for public health and environmental advocates — and for the Environmental Protection Agency.

“It’s a big win for the EPA, and not just because it has to do with this rule,” the director of the environmental law program at Harvard, Jody Freeman, told The New York Times. “It’s the fact that it’s setting the stage and creating momentum for what’s to come.”

In the 6-2 decision, the court ruled that the EPA has the authority to regulate emissions from fossil-fuel burning power plants that drift across state lines — to states that may not share in a power plant’s benefits (e.g., jobs and energy for the surrounding area). In some East Coast cities, such as New Haven, Conn., 93 percent of air pollution comes from out-of-state sources.

As Justice Ruth Bader Ginsberg explained in the majority opinion:

Left unregulated, the emitting or upwind State reaps the benefits of the economic activity causing the pollution without bearing all the costs. … Conversely, downwind States to which the pollution travels are unable to achieve clean air because of the influx of out-of-state pollution they lack authority to con­trol. … To tackle the problem, Congress included a Good Neighbor Provision in the Clean Air Act (Act or CAA). That provision, in its current phrasing, instructs States to prohibit in-state sources “from emitting any air pollutant in amounts which will . . . contribute significantly” to downwind States’ “nonattainment . . . , or interfere with maintenance,” of any EPA-promulgated national air quality standard.

The ruling overturned a lower court decision that Washington Post columnist Steven Pearlstein characterized as an act of “judicial jihad” on behalf of Big Coal. The US Court of Appeals for the District of Columbia ruled in 2012 that the EPA did not have the authority to impose these rules, arguing in part that the rules might require a state to eliminate more interstate pollution then it produces. Experts concluded, however, that this possibility was “extremely unlikely”; the Justice Department said raising the possibility was “an attack on a straw man.”

The EPA had concluded in 2012 that the new rules would result in “$120 to $280 billion in annual benefits, including the value of avoiding 13,000 to 34,000 premature deaths each year.” Within two years of implementation, the agency predicted a drop in “SO 2 [sulfur dioxide] emissions by 73 percent from 2005 levels” and “power plant NO X [nitrogen oxide] emissions… by 54 percent.” EPA administrator Gina McCarthy said yesterday’s ruling was “a resounding victory for public health.”

In his dissent, Justice Antonin Scalia (who was joined by Justice Clarence Thomas) suggested that the mathematics behind the state-by-state requirements were burdensome, and had echoes of Marxism. Talking Points Memo’s Sahil Kapur also noted that Scalia’s dissent, which argued that the majority opinion was inconsistent with precedent, was based in part on a factual error, which was corrected in the text of the dissenting opinion by the morning after the ruling.

The decision dovetails with recent efforts by the agency to tighten its regulation of the coal industry in Obama’s second term. As it became clear early in Obama’s presidency that any legislation confronting the reality of climate change was off the table, they shifted to the Environmental Protection Agency (EPA) to take whatever action it could through more-stringent regulation.

A prime example are limits on emissions from new power plants that were finalized earlier this year. New regulations on already-operating plants are expected in June.

But while this week’s ruling is a victory for the administration and public health advocates — which it is — it’s only a small step toward tackling what will become (and probably already is) the most pressing issue for America, and all nations, to address: our dependence on fossil fuels, and its disastrous consequences. The EPA can only do so much with regulations based on decades-old laws like the Clean Air Act. New laws are needed. But as ExxonMobil recently opined, those laws don’t seem likely any time soon.