Before the lights went down in the New York University Law School auditorium on Tuesday evening, two guests scooted into reserved seats on the end of the fourth row. Once Malia Obama and Harvey Weinstein took their seats, a few spaces down from where Monica Lewinsky had settled in, and two rows behind CNN’s Don Lemon, the room dimmed and stage lights emerged on Vanity Fair editor Graydon Carter. “Good evening and welcome to the resistance,” he told the crowd.

On this early spring evening in downtown Manhattan, Carter was moderating a panel for the National Resources Defense Council about environmental issues under President Donald Trump. A week earlier, Trump had signed a sweeping executive order rolling back a handful of Obama-era decrees regarding climate change and carbon emissions. The order, which kicks off a review of the Clean Power Plan, and pulls back a moratorium on coal mining on federal land, is one crumb of what NRDC president Rhea Suh called “ridiculous and unlawful” environmental policy.

The panel, which included Suh; Discovery Communications C.E.O. David Zaslav; former senior Obama advisor Brian Deese; and author and environmentalist Bill McKibben, quickly turned to facts. All of the panelists pointed out ways in which the Trump administration has succeeded by bending them, and how the resistance can fight back and make changes despite headwinds from the White House and Republican-led Congress.

NRDC’s Mitch Bernard, for example, told the audience that the group has already filed five lawsuits against the Trump administration, and that the pace of litigation will only accelerate. Not only does the organization plan on continuing to sue the government, but they will also file suits against private polluters, as well. “In court,” he said, “facts matter. Evidence matters. Science matters. A tweet doesn’t matter. Judges don’t decide things based on alternative facts.” The room broke into applause when Bernard pointed out that “the speed with which [the Trump administration] is recklessly violating laws is astounding.” He continued: “and we’re going to meet them at the courthouse door.”

Part of this strategy entails using legislation to tell stories. Suh pointed to a 38-year-old mother of three from Flint, Michigan who worked with the NRDC to talk about how her 7-year-old son broke his wrist from falling off a bike. “His bones were so brittle from the water that his wrist shattered,” she said. Zaslav and his team at Discovery have been focusing on this kind of fact-based storytelling, including an upcoming documentary on mosquitos, which are now one of the deadliest animals on earth on account of climate change. “If we point out the factual impacts on the environment and animals, everyone will raise their hand and say they get that—Republicans and Democrats.”

So how can those concerned and mobilized to protect the environment in the Trump era do something? “We need bodies,” McKibben said. “People need to be fighting on nights and weekends. For the foreseeable future, weekends are for fighting fascism.”