The Wall Street Journal Law Blog has a post criticizing Judge Richard Sullivan: "To Lawyers Who Represent Cooperators: Fear Judge Richard Sullivan." The Journal blogger seems upset that a judge actually takes seriously the judicial function.
The United States Constitution was founded up on separation of powers. No one branch of government should become too powerful. "No political truth is certainly of greater intrinsic value or is stamped with the authority of more enlightened patrons of liberty." The Federalist No. 47, p. 324 (J. Cooke ed. 1961). As a member of the Judicial Branch, Judge Sullivan has the power to veto plea agreements.
Separation of powers, "does not mean that these departments ought to have no partial agency in, or no controul over the acts of each other." The Federalist No. 47, pp. 325-326 (J. Cooke ed. 1961). Currently plea-bargaining means that the prosecutor gets to decide whether, when, and for how long a person is going to prison. If a prosecutor doesn't want you to go to prison, she simply won't prosecute you. If the prosecutor wants you to go to prison for decades, she will overcharge you. Prosecutors are poweful, but not all-powerful. Judges have power, too.
That said, some defense lawyers have suggested to the Law Blog that Sullivan’s conduct may have a chilling effect on cooperation agreements, if criminals believe the government can’t help them get more-favorable treatment by judges. Sullivan declined to comment to the Law Blog.