(CNN) Roy Moore, the Republican nominee in Alabama's Senate election, signed onto a resolution in 2010 affirming the right of states to nullify, or void, federal law, CNN's KFile has found.

"We pledge to limit and restrain all federal government exercise of power that exceeds in any way the plain language of those few powers listed in the Constitution and to nullify all others that exceed such limit," read the resolution signed by Moore at the 2010 Tenth Amendment Summit. Moore was running for governor of Alabama at the time.

The 2010 resolution is Moore's most explicit affirmation of nullification, a theory with a long and controversial history in the United States. In practice, Moore's willingness to defy federal authority has twice caused his removal from the Alabama Supreme Court. In 2003, Moore refused to take down a monument to the Ten Commandments from inside the court building and was stripped of his chief justice position by the Alabama Court of the Judiciary. In 2016, Moore, a hardline opponent of LGBT rights, was suspended by the same panel for ordering state judges to defy the US Supreme Court's ruling legalizing same-sex marriage. He later resigned to run for Senate.

Never upheld in federal court and criticized by many constitutional scholars, the idea's most famous test came in the 1830s, when South Carolina, led by Senator John C. Calhoun, sparked a crisis by declaring null two federal tariffs. Congress responded by authorizing President Andrew Jackson to collect the tariffs with military force. A compromise tariff ultimately ended the crisis without violence in 1833.

Previously resurrected by segregationists during the civil rights movement, nullification has seen another resurgence in conservative thought in recent years, fueled by the so-called "Tenther" movement and organizations like the Tenth Amendment Center. Some state legislatures have passed non-binding resolutions asserting their sovereignty under the Tenth Amendment, including Alabama in 2010, a move that Moore praised

Two constitutional scholars told CNN that they considered Moore's support of nullification "extreme."

"Moore's remarks entirely ignore the dramatic expansion of the powers of the national government in the aftermath of the Civil War, and expressed in the Thirteenth, Fourteenth, and Fifteenth Amendments to the Constitution," Bruce Ackerman, Sterling professor of law and political science at Yale, told CNN. He added that Moore's "effort to turn back the clock 150 years is very extreme indeed."

Steven D. Schwinn, a professor of Law at The John Marshall Law School, said, "Moore's positions are well outside the mainstream of constitutional thought and lack any support in the text, rulings, or history of our Constitution. I certainly consider these positions extreme, especially for a judge or candidate for office."

Another scholar, dean of Berkeley Law Erwin Chemerinsky, said, "Federal law is supreme over state law, period. States have no sovereignty to interpose to nullify federal law. This is a theory that has been rejected throughout American history."

A spokesperson for the Moore campaign did not return a request for comment.

The Tenth Amendment Summit was held that February in Atlanta by the Tenth Amendment Center, a group that describes itself as "the nation's leading source for constitutional education and nullification activism." The event's sponsor was Ray McBerry, then a Georgia gubernatorial candidate and board member of the group the League of the South, a group that advocates Southern secession to form an independent country. Fox News commentator Andrew Napolitano was originally slated to speak but did not attend.

In addition to pledging to nullify certain federal actions, the Tenth Amendment Summit resolution stated that the "federal government has seized unlimited power over virtually every aspect of Americans' lives in violation of the Constitution of the United States, specifically with respect to the Tenth Amendment."

Moore also spoke at the event, predicting that a dystopian future could await his audience if they did not resist the intrusions of the federal government.

"I say again, we must fight," he said. "An appeal to the God of Hosts is all that is left us. They tell us that we're weak, unable to cope with so formidable an adversary, but when should we be stronger? Would it be the next week? Or the next year? When will it be? When we are totally disarmed, under UN Guard that's stationed at every house?"

McBerry, who has argued that the Civil War was not fought over slavery and was instead about some of the same federal versus state issues "we are debating today," also signed the resolution. The League of the South advertised the summit on its blog in January in a post saying, "Judge Andrew Napolitano, Judge Roy Moore, and our very own Ray McBerry will speak at the Tenth Amendment Summit to be held February 25-26, 2010 at the Airport Hilton in Atlanta, Georgia."

Moore praised McBerry in his speech at the event, presenting him as a leader in standing up for the Tenth Amendment and telling the audience that "people like Ray McBerry and these candidates, they do need your support. They do need it and they deserve it because they're running against the same mountain of obstacles that I run against."

Though he did not explicitly mention nullification in the speech, Moore railed against federal overreach.

"The war is inevitable, let it come," he said. "This is not necessarily a war to be fought with guns and knives and cannons. This is a war over our Constitution, and we're on the right side. We're on the side of our forefathers, and the side that they determined was best for our country. The federal government is simply going their own way. It is in vain to extenuate the matter."

Moore elaborated on his view of how states should respond to federal overreach at a 2014 law summit with attorney Herb Titus, the 1996 Constitution Party vice presidential candidate, at First Baptist Church in Crestview, Florida. In that talk, Moore explained when he thinks dramatic steps like secession and armed revolution are justified, saying that they should be considered a last resort.

He asked the audience what they thought of secession, before approvingly quoting an 1825 letter from Thomas Jefferson to William Giles which advocated separation "from our companions only when the sole alternatives left are the dissolution of our union with them, or submission to a government without limitation of powers."

Moore cast his refusal to the remove the Ten Commandments monument as a form of interposition, a concept similar to nullification holding that states can assert their authority to prevent the federal government from intruding on it. Moore called interposition "the step before outright revolution."

He went on to say that he did not believe revolution was necessary yet.

"Well, I'll submit to you that the history of the present United States Supreme Court, and legislature, is the history of repeated injuries and usurpation," he said, referencing the language of the Declaration of Independence. "All having in direct object the establishment of an absolute tyranny over the states. I'm not arguing for revolution. I'm saying that we put up with it as long as we can go. Have we reached that point? Well, maybe not yet, because we can still interpose."