Just having read Gore Vidal's 'Burr', I get the impression that Jefferson was acting against Burr(Writing to Congress that Burr was a traitor, before the trial had begun), with personal vendetta.The trial was almost a disaster for Jefferson with the chief witness for the prosecution Gen Wilkinson only averting indictment for treason only by a very thin margin, and by Wilkinson's tampering of the letters of Burr gave the impression that the government was trying to frame Burr.