The answer lies in the firing earlier this year of Jessie Liu, the former U.S. Attorney for the District of Columbia. By firing Liu, Barr and his team took control of the Washington, D.C., U.S. attorney’s office. Until they did that, the office was following up on various indictments and charges that had been brought against Trump’s associates. Once they seized control, Barr’s team intervened to short-circuit that process. They interceded in the sentencing of Roger Stone, and more recently, they have made an effort to dismiss the case against Michael Flynn. In both circumstances, career prosecutors were so outraged that they withdrew from the case, and some resigned from the Department of Justice altogether.
This is how an authoritarian works to subvert justice. He purports to uphold the forms of justice (in this case, the formal rule that the attorney general and the president exercise hierarchical control over the U.S. attorneys) while undermining the substance of justice. In the Flynn case, for example, Barr has asserted an absolute, unreviewable authority to bring and dismiss cases at will—a power that, even if legally well founded, is a subversion of justice when misused.
That may be the game plan for New York as well. Barr may want Berman out so that he can use his newly enhanced control to dismiss or short-circuit all of the pending cases in Manhattan that implicate Trump or his associates.
We know those are many.