Youth climate activists who are suing the U.S. government over inaction on climate change are pushing to move their case to trial — and they offered up hundreds of pages of the federal government’s own pronouncements as evidence a delay is making things worse.

The plaintiffs say the federal government’s energy policies promote and exacerbate climate change and infringe on the youths’ constitutional rights.

At a June hearing in Portland, a panel of three judges for the 9th U.S. Circuit Court of Appeals heard oral arguments on an appeal and a preliminary injunction in the case. The plaintiffs have been waiting for a decision since.

"Another six months have passed without decision while defendants continue to act in ways that further endanger plaintiffs' lives, liberties, and property, as supported by additional, new evidence," the youths said in a court filing in the San Francisco federal appeals court this weekend.

This latest filing cites a lengthy list of public government documents that the plaintiffs say show federal expansion of oil and gas exploration and production on federal lands and a demonstrated increase in coal extraction. The evidence increases the urgency of the case, they said in the filing.

Eugene lawyer Julia Ann Olson has spearheaded the case. Her clients claim that through persistent inaction on the climate crisis, the federal government has infringed on their constitutional right to a sustainable climate. The youth want the court to order the United States to prepare a comprehensive energy plan that transitions the nation away from fossil fuels.

The landmark case is pushing the courts to take action in uncharted territory -- to force the hand of the executive branch. At the June 4 hearing, Judge Andrew D. Hurwitz told Oslon: “You present compelling evidence that we have a real problem, compelling evidence that we have inaction by the other two branches of government. It may even rise to criminal neglect. The tough question for me, and I suspect for my colleagues, is do we get to act because of that.’’

Lead plaintiff and University of Oregon student Kelsey Rose Juliana, 23, first filed the case with Olson in 2015 in federal court in Eugene. Since then, the federal government -- via both the Barack Obama and Donald Trump administrations -- has sought to quash the case.

Lawyers representing the U.S. Department of Justice have argued the courts do not have the authority to compel the executive branch to cut greenhouse gas emissions from the U.S. economy. Assistant Attorney General Jeffrey Bosset Clark Sr. called the case a direct attack on the federal power structure and the separation of the executive and judicial branches. He argued at the June hearing that it would subvert due process and ignore the administrative laws and procedures that are guidelines for the country’s energy policies.

The case was fast-tracked in January after the youth filed a motion to expedite. Many legal experts expect the landmark case will eventually land in front of the Supreme Court’s nine justices.

The government appealed a ruling last October by U.S. District Judge Ann L. Aiken which allows the case to proceed to trial.

But Aiken also dismissed President Donald Trump as a defendant, citing respect for the separation of powers and calling his involvement non-essential because lower-level government officials carried out the challenged policies.

-- Emily Goodykoontz; 503-221-6652; egoodykoontz@oregonian.com

Maxine Bernstein contributed to this report.