Mr. Giuliani has claimed, without evidence, that Mr. Biden’s push to oust Mr. Shokin was an attempt to block scrutiny of his son’s actions. In fact, Mr. Biden was just one of many officials calling for Mr. Shokin to go. Good-government activists were protesting his actions in the streets, as were eurozone power players like Christine Lagarde, then the managing director of the International Monetary Fund, along with Ms. Nuland and Senate Republicans.

“The position regarding getting rid of Shokin was not Vice President Biden’s position; it was the position of the U.S. government, as well as the European Union and international financial institutions,” said Amos J. Hochstein, former coordinator for international energy affairs at the State Department and one of the few administration officials who directly confronted Mr. Biden at the time about his son…

Mr. Biden’s advisers say that he and his son had informally agreed years earlier not to discuss anything pertaining to the younger Mr. Biden’s business activities, as a way to insulate them both.

Bob Bauer, former Obama White House counsel and Biden adviser, said that even pressuring Hunter Biden to quit the board would have constituted a breach of that firewall, and suggested that was one of the reasons the vice president chose not to do it. “The independent activities of an adult child simply don’t create a ‘conflict of interest’ for the parent who is a public official,” he said. “And as a matter of sound ethical practice, it is important for officials in this position to maintain that distance: to be able to show that, in doing their jobs, they could not have been affected by discussions or involvement with their adult children relating to private business matters. Their posture has to be, ‘Whatever you decide to do, I am going to do what I have to do.’”