he department also took on lawsuits over books written by Trump adversaries. In the case of the former national security adviser John R. Bolton, who had fallen out of Mr. Trump’s favor, it opened a criminal inquiry into whether he illegally disclosed classified information.Being a successful attorney general “is not just about doing the right thing, it’s about preserving the legitimacy of the institution,” Ms. Roiphe said. “Even if he honestly held these beliefs, he addressed them in ways that were only respected by his own political followers.”Some Justice Department officials believed that Mr. Barr privately honed the president’s belief that his attorney general was his political fixer and used that capital with Mr. Trump to protect the department, shielding it from blowback when it prosecuted cases that interfered in trade negotiations with China and to protect the F.B.I. director, Christopher A. Wray, from being fired over the president’s animosity toward the bureau.