A water intake pipe for oil sands operations leads downhill to the Athabasca River on April 28th, 2015, north of Fort McMurray, Canada. (Photo: Ian Williams/Getty Images)

A climate activist who was convicted after turning off an oil pipeline won the right in April to argue in a new trial that his actions were justified. The Washington State Court of Appeals ruled that Ken Ward will be permitted to explain to a jury that, while he did illegally stop the flow of tar sands oil from Canada into the United States, his action was necessary to slow catastrophic climate change.

This legal argument has deep roots: History is full of situations in which breaking the law was morally justified, and a critical means of changing unjust laws. The abolition movement, the women's suffrage movement, and the civil rights movement of the 1960s all included protests, sit-ins, and other acts of non-violent civil disobedience. Each of these movements saw activists jailed and prosecuted for challenging laws that were changed as a result. While controversial at the time, these struggles are now understood as heroic efforts that led to major milestones in human rights.

What many people don't realize is that, in such situations, breaking the law can be legally, as well as morally, permissible, and our legal system recognizes that breaking the law is sometimes justified. Climate change activists have begun using a legal argument called the "necessity defense," which justifies non-violent action taken to prevent a greater harm.

Similarly, humanitarian workers with the group No More Deaths, who were recently arrested for leaving water in the desert near the U.S.–Mexico border, argue that their efforts to save migrant lives are justified by the necessity doctrine. Under this argument, defendants can be acquitted of an act that is technically illegal. Like its better-known cousin, the doctrine of self-defense, it permits a judge and jury to consider context and morality.

Famous necessity cases date from the 1500s. In recent decades, the argument has been used by activists fighting apartheid, nuclear proliferation, AIDS, and air pollution.

In 1986, protests against Central Intelligence Agency activity in Central America rocked the University of Massachusetts–Amherst. The demonstrators, including President Jimmy Carter's daughter Amy Carter, argued that their protests were meant to prevent the much more severe crimes being carried out by the CIA, including death squads, disappearances, and massacres—human rights abuses that helped enable the rise of U.S.-backed dictators. On her Massachusetts campus, Carter described seeing "60 or 80 cops in riot gear, billy clubs, mace, with four or five police dogs" and police beating an activist's head against a concrete wall. Ultimately, 15 of the peaceful protesters faced charges.

At their trial, these protesters used the necessity defense, providing evidence of CIA assassinations, kidnappings, and misinformation campaigns. They held that these crimes by the state constituted a greater harm to humanity than their peaceful protest had done. The defense also summoned experts, including a former U.S. attorney general, to establish that civil disobedience is an effective way to challenge injustice. Though the defendants freely admitted to their actions, all were found not guilty.

A juror from the trial later explained that the activity of the CIA had been "shocking and alarming" and that the jurors had come to admire the defendants' "integrity."

In the 1990s, clean air advocates launched a months-long series of protests at New York's Queensboro Bridge. In addition to petitions and a letter-writing campaign, citizens gathered at the bridge each week to protest the city's policies on pollution. The activists were motivated by the damage that pollution was causing to the people of New York. At their trial for disorderly conduct, the judge agreed that these activists had been addressing an overwhelming harm. Crucially, the judge also found that civil disobedience had been the only recourse open to the defendants: They had no lawful means available that could stop the harm, he said. The defendants were acquitted.

In these and other cases, courts or juries determined that a given "crime" had been necessary to prevent a greater harm. Today, climate activists argue that stopping fossil-fuel production is necessary in light of the overwhelming dangers of climate change. The necessity defense is the criminal legal system's built-in check that allows us to recognize an important truth: Sometimes, morality is more important than legal technicality.

In Washington State, Ward was barred from using the necessity argument in his first two trials. (The first ended in a hung jury, the second in a conviction for the lesser of two charges.) His new trial may be the first true test of the necessity defense by a climate activist before a jury.

As long as lives are imperiled by misguided and destructive policies, such as those that allow climate destruction, there will be advocates who break the law to follow their conscience. History proves that strict adherence to immoral laws can be foolhardy and destructive. Laws are not perfect. They evolve over time to reflect society's changing values. Our ability to act rationally and prioritize morality in the face of these contradictions is what moves us toward a more just world.

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