The Trump administration cannot short-circuit a federal climate change lawsuit brought by a group of 21 children and teenagers, an appellate court ruled on Wednesday, probably sending the ambitious case back to a lower court in Oregon for trial.

The federal government’s request to halt the lawsuit “is entirely premature,” wrote Judge Sidney Thomas, the chief judge of the U.S. Court of Appeals for the 9th Circuit.

“We’re looking forward to putting the federal government on trial on climate science and its dangerous fossil fuel policies,” said Julia Olson, the lead attorney for the young plaintiffs and chief counsel of Our Children’s Trust.

The Justice Department did not immediately respond to a request for comment on the court’s ruling.

In a suit originally brought against the Obama administration in 2015, the young plaintiffs assert that the government’s actions to promote fossil fuel emissions violate the basic constitutional rights of future generations. They were helped in the litigation by former NASA climate scientist James Hansen, whose granddaughter Sophie Kivlehan is one of the student plaintiffs.

The federal government had argued that the trial would entail burdensome requests for discovery and that the remedy requested by the young plaintiffs would violate the separation of powers since it effectively asks a court to direct the executive and legislative branches to do something about climate change. But in 2016 the U.S. District Court for the District of Oregon declined to dismiss the case and set it on a path toward a trial.

The Justice Department then sought a “writ of mandamus,” calling on the appellate court to stop the case before it could proceed further. This is generally considered an extraordinary remedy, and the 9th Circuit panel decided 3-0 that a halt was not justified in this case, and hard to justify in general.

“If appellate review could be invoked whenever a district court denied a motion to dismiss, we would be quickly overwhelmed with such requests, and the resolution of cases would be unnecessarily delayed,” the court said.

The case will probably proceed before the Oregon federal court, where the case was originally filed. Olson said she wants depositions from multiple representatives of top federal agencies, as well as from leading climate scientists. She expects discovery to take six months and a trial to begin after that. (It was originally set to begin last month.)

Olson said the case will attempt to show that the globe is warming because of human activities and that the U.S. government isn’t taking action, meaning Americans who are children today will see their most basic rights violated, such as life, liberty and the pursuit of happiness.

The case would put climate science on trial, but Olson said so far the Trump administration has not called the fundamentals of global warming into question. “Thus far, they have not been disputing climate science, or that it’s human-caused, but they haven’t yet taken a position on certain aspects of climate change and what’s projected,” she said.

The ruling is good news for advocates fighting climate change, but it certainly doesn’t mean they won’t be disappointed later in the extraordinary and unprecedented case.

“We are mindful that some of the plaintiffs’ claims as currently pleaded are quite broad, and some of the remedies the plaintiffs seek may not be available as redress,” wrote the appeals court. “However, the district court needs to consider those issues further in the first instance.”