Minutes into arguments, Justice Sonia Sotomayor raised the question of whether immunity extends to political assassinations.

The issue was discussed at length in a lower court hearing. Then, Trump attorney John Sauer suggested Trump could be immune, under certain circumstances.

"I'm going to give you a chance to say if you stay by it," Sotomayor said. "If the president decides that his rival is a corrupt person and he orders the military, or orders someone to assassinate him, is that within his official acts for which he can get immunity?"

"It would depend on the hypothetical, but we could see that could well be an official act," Sauer said.

Justice Ketanji Brown Jackson pressed Trump attorney John Sauer on his contention that without immunity all future presidents would feel paralyzed to take official acts while in office that could put them in criminal jeopardy.

"I mean, I understood that every president from the beginning of time essentially has understood that there was a threat of prosecution [upon leaving office]," Jackson said.

Sauer responded by quoting Benjamin Franklin from the constitutional convention, to which Jackson seemed skeptical.

"But since Benjamin Franklin everybody has presidents who have held the office [who knew] that they were taking this office subject to potential criminal prosecution, no?" she said.

Justice Clarence Thomas opened questioning by getting to the heart of the case: where is the "source" of presidential immunity and how would the court come to decide what acts fall under that scope.

First, he asked Trump's attorney to be "more precise as to the source" of supposed presidential immunity.

John Sauer responded that it comes from the executive vesting clause of the Constitution.

Thomas then pressed how exactly the court would "determine what an official act is," to which Sauer said acts fall within the “outer perimeter” of a president's official duties.

Trump's attorney, John Sauer, addressed the justices first, saying in his opening statement that unless presidents are granted the absolute immunity that Trump seeks, "Every current president will face de facto blackmail and extortion by his political rivals while he is still in office."

Sauer also called out controversial policies of other commanders in chief, such as George W. Bush's regarding the Iraq War and a Barack Obama-approved drone strike against a U.S. citizen as part of anti-terrorism operations overseas, while saying the implications of the court's decision here "extend far beyond the facts of this case."

Oral arguments have begun in Donald J. Trump v. United States.

Arguing for Trump is attorney D. John Sauer. Presenting for Smith is Michael R. Dreeben, who has argued more than 100 cases before the nation's high court.