In May of 2015, 20-year-old Western Washington University student Chiara D'Angelo hitched herself to an Arctic drilling support vessel's anchor chain and stayed there for 63 hours. Her goal was to stop or delay the ship leaving Bellingham for Shell's Arctic drilling mission in the Alaskan Arctic.

Before D'Angelo climbed up the chain, the US Coast Guard, anticipating that people would protest Shell's latest venture, created 100-yard "safety zones" around the fleet. Anyone who violated the safety zones could face stiff fines, or potentially criminal charges, the Coast Guard warned.

When D'Angelo finally peeled herself off the chain, the Coast Guard cited her for violating the safety zone—a potential $40,000 fine. On Monday, D'Angelo plans to contest the fine in a meeting with a Coast Guard hearing officer using a unique legal strategy: a climate "necessity" defense.

"We are going to be asking the Coast Guard hearing officer to consider that she attached herself to the Arctic Challenger because of the horrible impacts of climate change around the world," Amanda Schemkes, one of D'Angelo's lawyers, said. "We are already seeing the impacts of climate change, and Shell's plan to drill in the Arctic would not only mean disaster for the Arctic ecosystem, but for climate change globally."

The necessity defense, a defense that argues that a person simply had to break the law because of the greater harms that would have occurred otherwise, isn't uncommon. A typical necessity defense analogy goes something like this: If a house is on fire, a person should be allowed to break down the front door (trespass) to save someone from burning to death inside.

But a climate necessity defense is another animal. By arguing that climate protesters had to do everything in their power to stop the engines of climate change, including blocking oil trains or Arctic drilling vessels, the climate necessity defense asks that a jury recognize the greater harms posed by climate change itself. In January, five climate protesters from Everett presented a climate necessity defense in front of a six-person jury—the first time such a defense had ever been heard in the United States in open court. The judge did not allow the jury to consider that defense, but jurors acquitted the defendants on one out of two charges and several hugged those same defendants outside the courtroom after the trial concluded.

D'Angelo's meeting with the Coast Guard hearing officer is also a nontraditional setting for a necessity argument. D'Angelo faces a civil penalty, not a criminal one, and instead of being heard by a jury of her peers, it will be up to the hearing officer's discretion whether to waive the penalty or reduce the fine. Violating a federal safety zone carries a potential fine of $40,000, according to the Coast Guard's Lt. Dana Warr.

Warr said he didn't know whether a climate necessity defense had ever been used to argue a civil penalty from the Coast Guard. "The civil penalties are intended to be remedial," Warr said. "What that means is to cause the charged party to remedy the violation, and also to discourage the occurrence of future violations."

The hearing on Monday will take place in the Coast Guard's local offices, but it will be over video teleconference with a Coast Guard hearing officer in Arlington, Virginia. This won't be the last climate necessity defense used for a Coast Guard penalty, either. Debra D'Angelo, Chiara D'Angelo's mother, faces a hearing with the Coast Guard on March 18, and Matt Fuller, a supporter of D'Angelo's who also stayed on the same anchor chain for 22 hours, will argue the same defense with the Coast Guard on March 17.