In a decision that is being called "groundbreaking" and "precedent-setting," a district court judge in Minnesota has ruled that he will allow oil pipeline protesters to present a "necessity defense" for charges related to a multi-state action by climate activists last October.

"Finally, we'll get to bring climate experts into a court of law, to describe the distance between our current reality and what physics demands of us if we hope to leave a stable planet for our kids."

—Emily Johnston, defendant

In his decision last week, Judge Robert Tiffany ruled that four activists who participated in the #ShutItDown action—in which pipelines across five states were temporarily disabled, halting the flow of tar sands oil from Canada into the U.S.—may present scientists and other expert witnesses to explain the immediate threat of climate change to justify their action.

"The ruling is only the third time a judge in the United States has allowed for such a defense in a climate case," InsideClimateNews reports. "The first case, in Massachusetts in 2014, did not go to trial after the prosecutor dropped the charges. A judge allowed the necessity defense in a Washington State case in 2016 but then instructed jurors they could not acquit on necessity."

This is the third "valve turner" case to go to court, but the first time a necessity defense has been allowed for this group of activists. Earlier this year, valve turner Ken Ward was convicted of one felony in Washington state.

In North Dakota earlier this month, valve turner Michael Foster was convicted of two felonies and a misdemeanor, while Sam Jessup, who livestreamed Foster's protest, was convicted of one felony and one misdemeanor. Climate experts including Dr. James Hansen—"the father of modern climate change awareness"—traveled to North Dakota to appear in court but were barred from testifying.

This latest case in Minnesota involves valve turners Emily Johnston and Annette Klapstein as well as videographer Steve Liptay and support person Ben Joldersma, who will be tried separately but are also allowed to present a necessity defense.

"What we did is not in dispute," said Klapstein. "The only question before the jury will be whether our action was necessary to prevent imminent climate catastrophe. Now we'll be able to present evidence connecting the devastation we're seeing—from hurricanes in the Caribbean to wildfires throughout western North America—to an oil-soaked political system utterly failing to respond."

"Finally, we'll get to bring climate experts into a court of law, to describe the distance between our current reality and what physics demands of us if we hope to leave a stable planet for our kids," said Johnston. "Doing so means there's an outside chance we can bridge that distance—and we need every chance we can get."

Hansen—who told Common Dreams that he believes jurors would have found Foster and Jessup innocent if a necessity defense were allowed in that case—is expected to testify in support of the Minnesota defendants.

"The whole planet will be inside a single courtroom the day this trial begins," said climate activist Bill McKibben, another potential expert witness. "It's a rare chance to explain precisely why we need to act, and act now."