FALL RIVER, Mass. � When Ken Ward and Jonathan �Jay� O�Hara go on trial here on Monday for blocking a coal shipment to Brayton Point Power Station, they won�t deny that for several hours on a spring day...

FALL RIVER, Mass. � When Ken Ward and Jonathan �Jay� O�Hara go on trial here on Monday for blocking a coal shipment to Brayton Point Power Station, they won�t deny that for several hours on a spring day in 2013 they anchored a tiny lobster boat in the path of a gigantic freighter that was trying to make a delivery to New England�s largest coal-fired power plant.

But the two environmental activists will argue that their actions were justified because of the threat posed to the planet by the burning of fossil fuels. Their lawyer will attempt to convince a jury in Fall River District Court that by blocking the way of the 689-foot Energy Enterprise with its cargo of 40,000 tons of coal Ward and O�Hara were working for the public good to combat climate change.

It�s a novel use of what�s known as the �necessity defense� � a long-standing doctrine that allows that in some instances by breaking the law a greater harm is being prevented. The strategy has been used successfully in other cases, but the trial of Ward and O�Hara on charges of disturbing the peace, conspiracy, failure to avoid collision and negligent operation of a motor vehicle may be the first time it will be invoked in a United States courtroom in connection to carbon emissions and global warming.

�We�re not going to be contesting the facts of the case,� O�Hara, a 32-year-old sailmaker who lives in Bourne, Mass., said in an online video. �But we are going to be arguing that it was absolutely necessary for public well-being and public safety to shut this plant down and stop this coal.�

�We were actually trying to stop the harm,� Ward, a 57-year-old former director of the Rhode Island-based Apeiron Institute for Sustainable Living who now lives in Oregon, said in the same video.

Henry David T.

In 2013, environmental groups from around New England targeted a series of protests against Somerset�s Brayton Point station, which opened in 1963 and, at its peak, supplied power to 1.5 million homes while becoming the largest air polluter in the region.

On the morning of May 15, Ward, who has also served as deputy director of Greenpeace USA, and O�Hara sailed a 32-foot lobster boat, the Henry David T., from Newport to the shipping channel that leads to the power station. They dropped a 200-pound mushroom anchor into the water and called the Somerset police to alert them to their peaceful protest.

Sometime before noon, the Energy Enterprise arrived with its delivery of coal from West Virginia, and for the next six hours, the lobster boat, flying an American flag and a banner reading �#coalisstupid,� bobbed in the water in front of the looming black hull of the massive freighter.

Finally, a salvage barge called in by the Coast Guard hauled the Henry David T.�s anchor aboard with a crane. The freighter wasn�t able to deliver the coal until the next day.

Neither Ward nor O�Hara was arrested, but the police later filed the four misdemeanor charges against them. They could face more than six months in prison if found guilty.

Ward and O�Hara declined comment through a representative of the Better Future Project, a Cambridge, Mass.-based environmental group that is supporting them in the trial. The pair�s lawyer, Matt Pawa, also said he would withhold speaking to the media until after the case. When pressed about their unique defense, he wrote in an email only, �We are optimistic.�

Necessity defense

Though criminal law professor Andrew Horwitz said the necessity defense has a long history, he has never heard of it being argued before in a U.S. court in relation to climate change.

To explain the logic behind the defense, Horwitz, an assistant dean and professor of law at Roger Williams University School of Law, describes someone walking on the sidewalk who is confronted by a car veering into their path. To get out of the way, the pedestrian jumps into a homeowner�s garden. Under the law, he trespassed, but he only did it to save his life.

The defense was notably invoked in the 1991 trial of the organizers of a needle exchange program in Manhattan on charges of illegally possessing hypodermic needles. The defendants successfully argued that they were distributing clean needles to help prevent the spread of HIV.

�The struggle � and why these defenses rarely succeed � is that the nexus between action and plausible claim that you�re preventing the harm is hard to establish,� Horwitz said.

After environmental activist Tim DeChristopher was arrested in 2011 for disrupting a federal auction of oil and gas leases in Utah, he planned to argue that his actions were justified because of global warming. But the judge in his case barred him from making that argument, and DeChristopher was sentenced to two years in prison.

�The judge restricted our defense to what happened at the auction,� said DeChristopher, who was released from prison in 2013 and is studying at the Harvard Divinity School. �We weren�t allowed to talk about all the factors that led into it.�

Although his attempt to use the defense failed, it has been used with success in the United Kingdom. In 2008, six Greenpeace activists who tried to shut down the Kingsnorth coal-fired power plant in England were acquitted after arguing that they were trying to prevent damage from climate change.

�There is an imminent danger from climate change,� said DeChristopher, who has become friends with Ward and O�Hara. �And it is becoming more obvious that our government is failing to respond to that challenge.�

Ward and O�Hara plan to call as a witness James Hansen, a leading climate scientist who also testified in the trial of the so-called Kingsnorth Six in the United Kingdom. Another prominent climate activist, Bill McKibben, the head of the nonprofit 350.org, is also expected to testify.

They have raised $10,250 in donations to support their defense and have called on supporters to attend the trial at the Fall River Justice Center. Several hundred people are expected to attend.

Last October, Ward and O�Hara in a way got what they wanted in regard to Brayton Point. The new owner of the power plant announced that it would close it down in 2017, citing the tough economics for coal in a region flooded with cheap natural gas.

But in the manifesto the pair released during their protest and in further postings on their website, lobsterboatblockade.org, they say they won�t be happy until the world stops burning coal altogether and averts what they believe is an immediate crisis.

Making that happen, they say, could take drastic action.

�We�re all asked to live within the correct restraints of what�s reasonable to talk about and reasonable to do,� Ward said on the video with O�Hara. �Well, if we keep doing that, the world will end.�

Correction: A previous version of this story incorrectly named defense lawyer Matt Pawa.