Environmental direct action will get a big legal test in Massachusetts next week when two men who temporarily blocked 40,000 tons of coal from reaching New England's largest coal-fired power plant stand trial.

Jay O'Hara and Ken Ward, both residents of southeastern Massachusetts, climbed aboard their 32-foot lobster boat at 6 a.m. on May 15, 2013, according to their website. They navigated to the ship channel and set their anchor between coal power plant Brayton Point in Somerset, Mass., and a 690-foot fully loaded coal freighter.

Their small boat, named the "Henry David T.," blocked the channel and the coal shipment until 6:30 p.m. while the freighter, named "Energy Enterprise," waited and the coast guard responded.

The pair, who declined to be interviewed for this article, were not arrested that day and were reported to have complied with the coast guard. But they were later arrested in July and arraigned on four charges: disturbing the peace, conspiracy, failure to avoid collision, and negligent operation of a motor vessel.

The two will go forward with a "necessity defense," according to their website. They claim that the action was a crucial component to a movement that led to the plant's closure, which is scheduled to take place in 2017, according to the Boston Business Journal.

"We're not going to be arguing to the jury that we weren't there; we're not going to be contesting the facts of the case," O'Hara says in a video explaining his and Ward's defense. "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 that coal."

They've lined up some climate celebrities to testify for them. Scientist James Hansen and writer Bill McKibben will both testify as experts in court on behalf of O'Hara and Ward.

Many of their arguments are distilled in The Coal is Stupid Manifesto, which O'Hara and Ward released the day of the action.

"We are on track to achieve a temperature increase of six degrees Celsius/11.8 degrees Fahrenheit by 2100, at least, and on a steep upward trajectory thereafter," the manifesto reads. "There is no question that without abrupt political change, a second flood of biblical proportions will erase the conditions in which life remotely like that we know now is made possible."

Burning coal, the manifesto continued, is the first thing that needs to happen to reverse that trend.

Another claim that Ward and O'Hara will have to support, for their necessity defense, is that they believed that by blocking the coal they had a chance to shut the plant down.

They may have good reason to believe they succeeded. A few months after the blockade, in October, 2013, owners of Brayton Point filed papers to shut down the plant, citing both economic and environmental reasons, according to a report by the Associated Press.

"We were not trying to make a statement; we were trying to shut down Brayton Point," Ward said in a video on the LobsterBoatBlockade website. "The odds of us doing it that day were low… but we did think it was possible we would help spark a broader political movement that would focus on shutting down Brayton Point and that in fact happened."

The pair's story has inspired many, including a song circle struck up at a Cambridge Unitarian Church this past Sunday, as well as significant media attention in the Boston area and elsewhere.

On August 17, the Boston Globe published an article in its Ideas section about the upcoming trial and the necessity defense strategy being employed by Ward and O'Hara.

The author, Joseph E. Hamilton, wrote that the trial will be a first for the "necessity" defense.

"Traditionally, this defense is used for situations like a prisoner fleeing from a burning jail, but Wood and O'Hara's lawyers will make the more sweeping argument that their illegal interference with a coal delivery was justified in light of the greater danger of catastrophic climate change."

Judges have disallowed using such a defense in previous climate protest cases, but in this instance, the defense has been unchallenged, Hamilton continued.

One of Hamilton's conclusions was that use of the defense won't necessarily lead to an acquittal, but that it will give Ward and O'Hara the opportunity to put the government on trial – and to show that current climate policy, one based largely on inaction, is unacceptable.

The trial will take place starting at 9 a.m. on Monday, Sept. 8, at the Fall River Justice Center located at 186 S. Main St. in Fall River, Mass. It is scheduled to continue into Tuesday.

O'Hara and Ward posted an invitation to the trial on their website, encouraging activists to dress formally for court and to "leave the signs and chants at home."

"This is serious business, and we are going to act seriously," the invitation reads. "Obviously it's serious for us – we are potentially facing months in prison – but it is more serious for our movement, as we have to make the case that half-measures and superficial victories simply are unacceptable."

For more information go to lobsterboatblockade.org.