Last week, as hundreds of thousands of protesters descended on Washington, DC for the People’s Climate March, 14 young Americans, ranging in age from 9 to 21, held a press conference in front the Supreme Court.

“We are not going to wait until someone in office is representing our voices,” 16-year-old Xiuhtzcatl Martinez told the assembled crowd of reporters, activists, and four US senators. “We need the action to come today. The threat upon our future is happening right now.”

Martinez and the 13 teens and tweens by his side were among 21 plaintiffs suing the US government to force it to take action on climate change. The government has known about the threat of climate change for decades, they argue, but has continued to take actions that contribute to climate change — like approving pipelines and subsidizing the fossil fuel industry — imperiling the lives of young Americans and future generations.

This, lawyers for these young plaintiffs allege, has violated their constitutional right to a habitable climate. The lawyers also argue that the atmosphere is a public trust, and that by continuing to allow American businesses to spew greenhouse gases into the atmosphere the government has neglected its responsibility to protect this resource. The kids want immediate steps to bring CO2 levels in the atmosphere down to 350 parts per million, the amount scientists consider safe to protect the planet from continued global warming. CO2 levels have risen well above 400 ppm.

These arguments are groundbreaking, and take environmental law into areas it’s never been. But judges have also signaled that the arguments may hold up in court. Last November, Federal District Judge Ann Aiken allowed the case to move forward, ruling against a bid by the Obama administration to dismiss the case. In her decision, she argued that the lawsuit was “no ordinary lawsuit,” continuing:

This action is of a different order than the typical environmental case. It alleges that defendants’ actions and inactions — whether or not they violate any specific statutory duty have so profoundly damaged our home planet that they threaten plaintiffs’ fundamental constitutional rights to life and liberty.

The ruling attracted the attention of environmental activists — Bill McKibben and Naomi Klein called the case “the most important lawsuit on the planet right now” — and legal scholars alike.

“Judge Aiken of the federal district court issued her decision on the government’s motion to dismiss they day after Donald Trump was elected president, and that decision was a ray of sunshine in what was a very dark day for the environmental community,” says Michael Burger, the executive director of Columbia University’s Sabin Center for Climate Change Law.

Though the suit was initially filed during the Obama administration, Donald Trump, a far greater foe of the environment, inherited the case. Aiken’s decision, Burger says, “offered some hope that the courts will stand as a bulwark against what will be a long, hard-fought battle — a real onslaught against environmental protections.”

The Trump administration has also been paying attention. In March, Jeffrey Wood, an acting assistant attorney general and former coal lobbyist, called on the court, again, to throw out the suit, saying he hoped to “avoid litigation that is unprecedented in its scope and in its potential to be protracted, expensive and disruptive to the continuing operation of the United States government.” Earlier this week, however, the court issued an opinion indicating that it is unlikely to do so; instead, the case is expected to go to trial in federal district court in Oregon later this year.

Whatever the district court decides can be appealed to the 9th Circuit — and then, from there, to the Supreme Court, where the young plaintiffs gathered last Thursday. If the kids are lucky, their rally foreshadows things to come: Perhaps, sometime within the next few years, they’ll be back, standing in the same place, preparing to make their argument before the nine justices who deliberate within.

“In theory, courts aren’t for sale,” Sen. Sheldon Whitehouse (D-RI) told them, standing in front of the court’s columned entrance. But, Whitehouse said, since the Supreme Court’s Citizens United decision in 2010, which allowed unlimited and often undisclosed sums of money to flow into elections, the same cannot be said of Congress. The fossil fuel industry now wields tremendous influence over legislators’ careers and has inhibited climate action, Whitehouse said.

“We’re still fighting over there and I believe we will win because the people are with us, but oh, my, what a barricade of lies and dark money the fossil fuel industry has built around that place,” Whitehouse continued, nodding toward the Capitol across the street.

“That’s why this lawsuit is so important: Because when you get to court, facts matter. When you get to court, witnesses must tell the truth, or they can be punished. When you get to the court, lawyers even have to tell the truth, at least to the court. When you get to the court, spin can be cross-examined. When you get to court, industry nonsense can be exposed.”

The 21 young plaintiffs are supported in their case by a nonprofit group composed of lawyers and activists under the name Our Children’s Trust. The group was the brainchild of Julia Olson, an environmental lawyer who began to feel a growing need to take a more aggressive approach to climate change litigation in 2006, after watching Al Gore’s An Inconvenient Truth.

“When I watched that film it really occurred to me that the way the environmental law community was approaching the issue was just — I use the phrase ‘playing whack-a-mole,’ where we were just trying to stop individual fossil fuel projects or seek specific regulations,” Olson says. “And there was this huge global crisis that we needed a broader, bigger, coordinated approach.”

A colleague connected Olson to Mary Wood, a professor and director of Environmental and Natural Resources Law Center at the University of Oregon, who had been developing the theory of an atmospheric trust — the idea that the atmosphere is a public resource to be protected by the government. Wood, in turn, connected Olson to climate scientist James Hansen, one of the first researchers to go before Congress and sound the alarm that climate change had begun. Hansen eventually joined Our Children’s Trust’s suit against the federal government: Alongside the 21 young plaintiffs, Hansen’s name is on the suit as a “guardian for future generations” and for his granddaughter, who is also a plaintiff.

Our Children’s Trust has filed suits in all 50 states, in addition to the suit currently pending against the federal government. The group stated litigating in 2011, and, since then, climate change has moved from a future threat to one that is very much in the present — something the youths suing Trump can attest to.

For instance, in 2016, 14-year-old Jayden Foytlin from Rayne, Louisiana, was awakened when floods tied to climate change swamped her bedroom. Journey Zephier, 16, a member of the Yankton Sioux Tribe, is from Hawaii, and is also facing flooding from rising seas. “A lot of the houses on the coastline are very close to the beachline, and the beaches are slowly shrinking as the water keeps rising,” he says. “A lot of the backyards in the houses are already submerged.”

Another plaintiff, Miko Vergun, 15, lives in Beaverton, Oregon, but hails from the Marshall Islands and has family that still lives there. “A lot of people from the Marshall Islands have become climate refugees, and I want them to have a place that they can call home. That’s mostly why I am part of this lawsuit — I believe that my people deserve justice, after all the suffering they’ve been through,” Vergun says, also noting that the Marshall Islands were home to nuclear tests during the Cold War that reshaped the archipelago and displaced communities.

“The Marshall Islands are very narrow,” she says. “If there is a huge storm, going into the middle of the island would do nothing. You have nowhere to go. It’s very scary for these Marshallese, which is why many of them are moving.”

“I’d like to go back someday,” she continues. “If we don’t do anything about this issue, climate change, by the time I go back and visit family, the island that I was born in, Majuro — I may not be able to go back.”

Julia Olson, the attorney on Our Children’s Trust’s federal lawsuit, and Kelsey Juliana, the lead plaintiff, both hail from Oregon. So do several of the other kids whose names are on the suit. So when they stood before the Supreme Court last week, anticipating the battle that might take place within the building behind them in a few years, both of Oregon’s senators were there in support. But after watching the press conference for several minutes, Sen. Jeff Merkley hustled across the Capitol green to a shady area on the north side of the building, where Sens. Ed Markey (D-MA) and Bernie Sanders (I-VT) joined him to introduce an ambitious piece of legislation.

There, flanked by climate activists in town early for the march, he announced a bill to build an energy system driven solely by renewable energy. The bill, called the “100 by ’50 Act,” lays out a plan to bring the US to 100 percent renewable energy by the middle of this century.

As the crowd thinned out, Merkley took a few questions.

“Is there any chance of getting anyone from the other side of the aisle to work with you on this?” one person asked.

“Absolutely,” Merkley replied. “Because we’re going to be relying on all of you to fill the streets outside their offices, to fill their offices, to fill their inboxes, to fill their phone lines, to say how important this is.”

In reality, the bill’s chances of getting through Congress are slim. Democrats would have to win back control of both Houses, or convince enough Republicans of the necessity of climate action — quick climate action — that they’d vote for this bill. The bill is forward thinking and scientifically based — two things that aren’t often criteria for congressional action.

Merkley acknowledged as much in a Facebook post. “With an anti-science Congress and president in power right now, some might doubt that this is the right time to push for a bold new strategy to tackle climate change and make a massive fundamental shift in the way we produce energy,” he wrote when he announced plans to introduce the bill. “But the fact is, we don’t have four years to wait to begin this rapid transition. We must act now.”

The gridlock in Congress, despite the urgency of climate change, underscores the importance of taking the fight to the courts.

“It’s particularly important now, in light of this administration’s antagonism to continuing climate action at the federal level. There’s a real question: How can citizens compel the federal government to take action?” says Michael Burger, the Columbia Law professor. “At least at the moment, this is a theory that has legs.”

Kelsey Juliana, the 21-year-old lead plaintiff, is no fan of the president, but she says the lawsuit with her name on it has been getting quite a bit of attention since the climate change-denying billionaire took office. “That’s the one good thing: It has really lifted our case up and given our case even more importance and urgency,” she said.

The strategy has worked elsewhere; in 2015, a Dutch court ruled that climate science required the government of the Netherlands to work to cut emissions at a much faster pace. Other suits are pending around the world — just last month, a 9-year-old filed one in India.

One lingering question of the young Americans’ case is whether the Trump administration will argue against the scientific consensus on climate change. The EPA recently took down webpages related to climate science “to reflect EPA’s priorities under the leadership of President Trump and Administrator Pruitt” — which means, Our Children’s Trust lawyer Julia Olson says, she’ll have to ask for more during discovery. “It’s forcing us to ask for more information from the federal government when it’s no longer made available online.”

When the case does go to trial, Trump’s lawyers will face an interesting question: Deny science — which would mean misrepresenting facts before a judge — or accept the science the president himself rejects.

“It’s a losing case to argue against the science of climate change,” Burger says. From watching the Pruitt EPA’s early actions — including its decision, so far, not to undo the so-called endangerment finding, labeling climate change a public health threat — Burger suspects the Trump administration may already know this.

“You get the sense that they understand that fighting basic science in the courtroom will lose,” he says.