BISMARCK, N.D. (AP) — An American Indian activist and former U.S. congressional candidate in North Dakota accused of inciting a riot during protests against the Dakota Access oil pipeline says he'll seek to present a "necessity defense" — justifying a crime by arguing it prevented a greater harm.

Chase Iron Eyes has pleaded not guilty to inciting a riot and criminal trespassing. He could face more than five years in prison if convicted at trial in February. The pipeline has since begun carrying oil from North Dakota through South Dakota and Iowa to Illinois.

Pipeline protesters who try the necessity defense typically argue that the greater harm is climate change. Iron Eyes, a member of the Standing Rock Sioux tribe, says he hopes to show that civil disobedience was his only option to resist a pipeline's incursion on his ancestral lands. The prosecutor in the case didn't respond to a request for comment. A judge will hear arguments Nov. 3.

WHAT IS THE NECESSITY DEFENSE?

People who use it are trying to show the harm they caused is justified because a greater harm was avoided as a result.

It dates to the late 1800s in England, when two sailors were charged with murder after they stayed alive by killing and eating a third sailor marooned with them in a lifeboat.

IS IT RECOGNIZED BY THE COURTS?

The U.S. Supreme Court has said it's an "open question" whether federal courts have the authority to recognize a necessity defense not provided by law, according to North Dakota District Court Judge Laurie Fontaine.

Whether the defense is permitted by law in state courts varies, according to University of Mississippi law professor Michael Hoffheimer.

The main argument against the defense is that it gives people who don't like a particular law the chance to break it and then argue it was excusable.

The main argument in its favor is that there might be special circumstances in which there is a justifiable reason for breaking a law.

HOW IS IT USED NOW?

It is used most frequently in criminal cases — such as drunk driving and marijuana use — in which people argue that what they did was necessary to prevent some greater harm.

In one such case, the Minnesota Supreme Court in 2014 ruled against a woman who challenged the revocation of her driver's license after she drove while intoxicated to escape her abusive husband.

Defense attorneys also have tried the necessity defense when people illegally use marijuana, arguing that it was needed to treat a health problem. A 1976 District of Columbia court decision in favor of a person suffering from glaucoma was the first in the country to recognize the defense in a marijuana case, according to the National Organization for the Reform of Marijuana Laws.

The defense also has been used through the years by abortion clinic protesters. In a high-profile case in 2009, a judge ruled against its use in the trial of Scott Roeder, who confessed to killing an abortion-providing doctor in Kansas but argued it was necessary to save unborn children.

It was first attempted in a U.S. environmental case in 2009 when a climate change activist cited necessity in Utah. Alice Cherry, co-founder of the Climate Defense Project, said it has been attempted in similar cases in Washington state, New York, Montana, North Dakota and Minnesota. The Climate Defense Project even offers an educational guide on using the defense and says this area of the law is "developing rapidly."

With pipeline protests, demonstrators often point to climate change and environmental damage as the greater harms. Oil pipelines carry fossil fuels, including oil, which release gases that trap heat and contribute to climate change, they argue.

Iron Eyes' arguments are more complex. He cites an "imminent threat" to his tribe's water supply because the Dakota Access pipeline goes beneath the Lake Oahe reservoir on the Missouri River, from which the tribe draws its drinking water. He also contends there was an effort by industry, private security and public law enforcement to conduct "an anti-terrorist campaign against Native Americans."

WHAT MUST BE PROVEN?

Legal experts agree the necessity defense is a long shot.

To succeed, the defendant generally has to persuade the judge or jury that they had no legal alternative to breaking the law. They also must prove they were trying to prevent some imminent harm, and there must be a direct connection between their breaking the law and preventing the harm. Finally, they must prove that breaking the law is less harmful than what would have happened.

HAS IT SUCCEEDED IN ENVIRONMENTAL CASES?

Not often.

In a Minnesota case, Judge Robert Tiffany is allowing four pipeline protesters to use the defense, but he also said they must clear a high legal bar. Tiffany said the defense applies "only in emergency situations where the peril is instant, overwhelming, and leaves no alternative but the conduct in question." That case is still pending.

A judge in Spokane, Washington, is allowing a 77-year-old Lutheran pastor to use a necessity defense in his upcoming trial stemming from a climate change protest last year. The Rev. George Taylor stood on railroad tracks to protest coal and oil trains that pass through Spokane and their contribution to climate change.

Judges in recent pipeline protest trials in North Dakota, Montana and Washington state have rejected the defense. The Montana judge said he didn't want to put U.S. energy policy on trial, and the North Dakota judge said a reasonable person couldn't conclude a direct cause and effect between the defendant's pipeline protest and climate change.

The Montana case is pending. In the Washington and North Dakota cases, the protesters on trial were allowed to tell jurors of their "state of mind" during the offense, but in both cases were still convicted. In the Washington case, the protester received probation and said he was "heartened, knowing that we are bringing these arguments into the jury system."

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Follow Blake Nicholson on Twitter at: http://twitter.com/NicholsonBlake .

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