Barr conveyed this position to Trump before resigning last month, sources say.
White House officials are also contemplating how the federal investigation into the insurrection affects other pardons Trump has discussed, such as for his personal attorney Rudy Giuliani who called for “trial by combat” at Wednesday’s rally before the Capitol was stormed.
“The situation in DC has raised issues within the White House even on the pardons,” one person close to the White House said.
Additional pardons are expected from the White House before Trump leaves office next week.
CNN did not immediately hear back from the White House and Barr did not immediately provide a comment to CNN.
The memo clearly states that under “the fundamental rule that no one may be a judge in his own case, the President cannot pardon himself.”
The memo does say, however, that a sitting president can resign the office and then be pardoned by his vice president once that person assumes the presidency. That is what happened when President Gerald Ford pardoned Richard Nixon in 1974.
Two separate sources close to Vice President Mike Pence say it is highly unlikely that Pence would issue a pardon to Trump in this scenario. Pence had been a loyal supporter of the President, but now feels frustrated and disappointed with Trump for his behavior around the insurrection and not calling to check on him during and after the riots, multiple sources said.
Trump could still pardon himself even if his administration officials don’t approve of the action. A self-pardon would only extend to federal crimes, and not protect Trump from state actions, including an investigation by New York state prosecutors into Trump’s personal and corporate finances. A self-pardon would also likely be contested in court.
Typically, the White House Counsel’s Office would ask the Justice Department’s Office of Legal Counsel to issue an opinion on weighty legal issues. This office is responsible for giving opinions on executive branch power, and in general tends to take an expansive view of presidential power.
Barr and Cipollone’s opposition to Trump pardoning himself is notable because both have been staunch defenders of Trump wielding an expansive executive authority during both the Russia probe and the 2020 impeachment proceedings over his call with the Ukrainian President.
Both men have recently been at odds with the President over his election lie. Barr left his post in December after publicly stating there was no widespread election fraud and Cipollone has considered resigning in recent weeks after strongly disagreeing with the President and his desire to use his office to overturn the election results.
This story has been updated.
CNN’s Evan Perez contributed to this report.