The U.S. Supreme Court handed environmentalists a major victory Feb. 27. Well, nearly. The real story is that the justices hit a triple, but we're not home yet. In an eagerly awaited decision, the court upheld the Environmental Protection Agency's (EPA) tough new standards for air pollution under the federal Clean Air Act. All nine justices agreed with the EPA's view that costs may not be considered when establishing air standards necessary to protect public health.

The court also unanimously reversed the lower court's conclusion that the act was overly vague, thus giving the agency lawmaking power that the Constitution grants solely to Congress. The court, though, made one final move: It invalidated the EPA's implementation plan for ozone, essentially delaying the day when that new standard will take effect. So what at first looks like a happy ending for the EPA, the environment and the public health, may in fact be just the beginning.

The court's decision is important because it allows the EPA to make protection of the public health its top priority when establishing air pollution standards. This is exactly what Congress intended when it first passed the act in 1970, and it makes sense. States consider costs later, when they implement the standards.

More good news: The court upheld the law against the constitutional challenge that Congress' delegation of authority was too broad. The Clean Air Act is one of the most specific statutes ever passed. Had the court invalidated the standards on this ground, it would have called into constitutional doubt innumerable federal statutes that are much more vaguely worded.

Now for the bad news. The court remanded the case back to the conservative appeals court, which may still invalidate the standards on other grounds. Even if itdoesn't, by striking down the EPA's plan to implement the new standard, the high court snatched defeat from the jaws of victory. A failure to implement the new standards is as bad as no standards at all, which is why the court's decision is so problematic.

To be sure, the implementation plan was not perfect. The EPA struggled mightily to reconcile conflicting provisions of the law and square Congress' specific timetables for complying with the old ozone standard with the need to now comply with a tougher one. The EPA's interpretation was sensible and should have been given a chance to work. Instead, the court sent the agency back to the drawing board.

It could be years until the EPA comes up with a new plan, and the Bush administration may take a different tack. Another lawsuit will inevitably follow. Industry can be expected to fight until the last dog dies. So if legal scholars and pundits claim that the Supreme Court delivered a home run to environmentalists, don't be fooled. The game isn't over yet.

Jody Freeman is a law professor; Timothy Malloy is acting professor of law and co-directs the Frank G. Wells Environmental Law Clinic at UCLA.