A federal appeals court has thrown out a high-profile case brought by 21 kids and young adults in a bid to block the federal government from encouraging the use of fossil fuels.

"Juliana vs. the United States," filed in 2015, alleges that the U.S. government knew for decades that burning fossil fuels would lead to damaging climate change but failed to do enough to stop it. Two judges out of a three-judge panel ruled that the issues raised in the case are best left to Congress.

"There is much to recommend the adoption of a comprehensive scheme to decrease fossil fuel emissions and combat climate change, both as a policy matter in general and a matter of national survival in particular," Judge Andrew D. Hurwitz wrote in the court opinion. "But it is beyond the power of an Article III court to order, design, supervise, or implement the plaintiffs' requested remedial plan. As the opinions of their experts make plain, any effective plan would necessarily require a host of complex policy decisions entrusted, for better or worse, to the wisdom and discretion of the executive and legislative branches."

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The lawyer for the plaintiffs has vowed to appeal the ruling, according to a Washington Post reporter.

Michael Gerrard, director of the Sabin Center for Climate Change Law at Columbia University, said in an email the "decision is a disappointment but not a surprise."

Gerrard added: "Many U.S. judges have vigorously enforced the environmental laws written by Congress but won't go beyond that. They want to leave the key decisions to the ballot box. So for now, all three branches of the federal government are sitting on their hands as the planet burns."

The plaintiffs have the option to request a hearing by the full Ninth Circuit Court of Appeals, or even ask the U.S. Supreme Court to hear their case. However, the high court's conservative lean make a pro-environment decision unlikely, Gerrard said.

"The case, while it was going, did bring great deal of public attention to the issue of climate change and the danger it poses to young people, so I think it did a lot of good," he said.

This the furthest that a climate-change case has advanced in U.S. courts on a legal theory known as the "public trust" doctrine — the idea that the government must protect some resources, like the air and water, for the well-being of all its citizens.

But last month, the highest court in the Netherlands invoked the theory, ordering the Dutch government to slash its greenhouse gas emissions. The court basing its ruling on the United Nations' climate convention and the government's responsibility to protect the lives and health its citizens.