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The Nuclear Regulatory Commission has been violating federal law by delaying a decision on a proposed nuclear waste dump in Nevada, a federal appeals court ruled Tuesday.

By a 2-1 vote, the U.S. Court of Appeals for the District of Columbia ordered the commission to complete the licensing process and approve or reject the Energy Department's application for a waste site at Nevada's Yucca Mountain.

In a sharply worded opinion, the court said the nuclear agency was "simply flouting the law" when it allowed the Obama administration to continue plans to close the proposed waste site 90 miles northwest of Las Vegas.  The action goes against a federal law designating Yucca Mountain as the nation's nuclear waste repository.

"The president may not decline to follow a statutory mandate or prohibition simply because of policy objections," Judge Brett M. Kavanaugh wrote in a majority opinion, which was joined Judge A. Raymond Randolph. Chief Judge Merrick B. Garland dissented in the case.

"It is no overstatement to say that our constitutional system of separation of powers would be significantly altered if we were to allow executive and independent agencies to disregard federal law in the manner asserted in this case by the Nuclear Regulatory Commission," Kavanaugh wrote.

A spokesman for the NRC said Tuesday the agency was reviewing the decision. He declined further comment.

The court's decision was hailed by supporters of the Yucca site, which has been the focus of a dispute that stretches back more than three decades. The government has spent an estimated $15 billion on the site but has never completed it. No waste is stored there.

"This decision reaffirms a fundamental truth: The president is not above the law," said South Carolina Attorney General Alan Wilson. The Obama administration "cannot pick and choose which laws to follow and which to ignore," Wilson said.

House Energy and Commerce Committee Chairman Rep. Fred Upton, R-Mich., and Environment and the Economy Subcommittee Chairman Rep. John Shimkus, R-Ill., also welcomed the court’s decision.

“Today’s action by the court is a significant milestone for Yucca Mountain and a clear rebuke of the Nuclear Regulatory Commission’s failure to implement the Nuclear Waste Policy Act,” they said in a joint statement. “The Obama administration rejected the law and prematurely terminated the Yucca Mountain repository program. But Congress and the courts have spoken out to prevent billions of taxpayer dollars and three decades of research from being squandered. … Let the science be the deciding factor on Yucca Mountain, not politics.”

South Carolina and Washington state filed a lawsuit seeking to force the NRC to rule on the Yucca Mountain application. The states both have large nuclear waste sites that would use the Yucca repository.

The Obama administration, under pressure from Senate Majority Leader Harry Reid of Nevada, abandoned the project early in the president's first term. In 2011, the NRC allowed the shutdown to stand, citing "budgetary limitations" imposed by Congress. The NRC is an independent agency that oversees commercial nuclear operations.

Reid, a Democrat, called the appeals court decision "fairly meaningless." Congress has cut funding for Yucca and is unlikely to restore it, Reid said.

"This isn't even a bump in the road. This, without being disrespectful to the court, means nothing," Reid told reporters at a clean energy conference Tuesday in Las Vegas.

Reid is a longtime opponent of the plan to bury waste at Yucca Mountain, which has drawn nearly unanimous opposition from Nevada elected officials.

Even if the Obama administration moves forward on the application, "there's no money" for Yucca Mountain, Reid said. "We've cut out funding for many years now and there's none in our budget to start it."

An attorney for the state of Washington, representing communities that support the dump, said the NRC violated a 1982 law requiring it to act on an application for construction of the Nevada site.

Kavanaugh and Randolph were appointed by Republican presidents, Garland by a Democrat.