To Defend Against a Mercurial Boss, Trump Aides Wield the Pen as Shield

Mr. McGahn said he kept notes because he was a “real lawyer,” explaining that they were not a bad thing.

Mr. Trump was unmoved. “I’ve had a lot of great lawyers, like Roy Cohn,” he said. “He did not take notes.”

Mr. McGahn’s notes of the conversation about notes, of course, ended up in Mr. Mueller’s hands, as did his notes of times when Mr. Trump tried to order him to fire Mr. Mueller and later lie about it. After Mr. Mueller’s report was released last week, the president lashed out. “Watch out for people that take so-called ‘notes,’ when the notes never existed until needed,” he wrote on Twitter.

Among those whose notes or memos were obtained by Mr. Mueller were Paul Manafort and Corey Lewandowski, two of Mr. Trump’s campaign managers; George Papadopoulos, a foreign policy adviser to the campaign; Reince Priebus, Mr. Trump’s first White House chief of staff, and John F. Kelly, his second; and Annie Donaldson, Mr. McGahn’s chief of staff.

Others included James B. Comey, the F.B.I. director fired by the president; Adm. Michael S. Rogers, the former director of the National Security Agency; Rob Porter, the former White House staff secretary; Stephen Miller, a senior adviser to the president; Jody Hunt, the former chief of staff to the attorney general; Tashina Gauhar, a Justice Department lawyer; and Mark Corallo, a former spokesman for the president’s private legal team.

Ms. Donaldson was known as a copious note-taker, whose constant documentation made colleagues anxious. Other aides said they were careful never to record anything while in the White House, but went home and wrote down conversations from earlier in the day to help store them in their memories — and then destroyed their notes before bed.

Mr. Lewandowski kept notes of one key conversation with Mr. Trump in his safe at home, “which he stated was his standard practice with sensitive items,” according to Mr. Mueller’s report. Admiral Rogers’s deputy was so stunned by a phone call that the two had with Mr. Trump about Russian intervention in the 2016 presidential election that he memorialized it in a memo signed by both men and stored in a safe.