William P. Barr will appear Tuesday before the Senate Judiciary Committee at his confirmation hearings for attorney general, where he will face strong questioning about a 19-page memo that attacks the legal basis of special counsel Robert S. Mueller III’s investigation. Those questions will correctly focus on Barr’s extravagant and absurd assertions of limitless — or what Barr calls “illimitable” — executive power. But there is another fatal flaw in Barr’s memo that casts grave doubt on his scholarship and his veracity. He misrepresents key facts of the impeachment proceedings against Richard M. Nixon in 1974 in order to limit the grounds for prosecuting President Trump. As a member of the House Judiciary Committee, I was a witness to that history and I know that Barr is not accurate.

Barr claims in his memo that presidents can’t be prosecuted for obstruction of justice on a basis of acts that don’t strictly involve impairment of evidence. Only inherently “bad acts” — such as destroying evidence or tampering with witnesses — are prosecutable, he asserts.

According to Barr, when the House Judiciary Committee drafted its articles of impeachment in July 1974, “the acts of obstruction alleged against” Nixon “were all such bad acts involving impairment of evidence.”