Ryan Bundy, who is acting as his own lawyer in the case, told the jury that for his part, he never sought to harm anyone, but felt a responsibility, derived from the principles of the Declaration of Independence — from which he quoted at length — to stand up to tyranny. “We had no intention to do evil, and the evidence will show this,” he said.

But federal prosecutors, in their opening presentation to the panel earlier on Tuesday, said the armed group had posed a threat of violence from the first day, when it cleared the refuge “at gunpoint,” until the final hours of the occupation, when the last holdouts told law enforcement officials that they were prepared to die.

The occupiers’ words and actions were never peaceful, Geoffrey A. Barrow, an assistant United States attorney, told the court. They trained in weapons and hand-to-hand combat while living at the refuge, Mr. Barrow said. They used earth movers to build defensive barricades.

“They wanted the world to know that they had taken it from the federal government,” he said.

The takeover of the refuge, in eastern Oregon, lasted nearly six weeks. It set off a national debate about homegrown right-wing militias, public lands, constitutional rights and police powers, especially after one of the occupiers, LaVoy Finicum, 54, was shot and killed by the Oregon State Police in late January after he raced his truck toward a police roadblock and then appeared to reach for his weapon.

In all, 26 people were indicted on felony conspiracy, weapons and theft charges — with the government contending that the occupiers conspired to impede federal employees at the refuge from performing their duties by using force, intimidation or threats, and that they stole government property and took weapons into a federal property.