Prosecutors in the federal system wield enormous power and possess an impressive array of investigative and prosecutorial tools for use at their discretion. However, as their discretion becomes greater, so does the risk of abuse. Consequently, there is a growing judicial temptation to supervise their behavior. This article addresses the proper scope of the supervisory power of federal judges in criminal investigations. The author first examines two examples of exercise of judicial authority by the Second Circuit to create rules in the criminal investigative setting. First in United States v. Hammad and then again in the most recent opinion in United States v. Ming He. Next, the author examines the escalating pressure on judges to supervise prosecutors--resulting directly from the Sentencing Guidelines--which warrants a direct revisit of the supervisory power. The author concludes, after looking at the origin and development of this source of judicial authority, that it is not nearly as broad as Hammad and Ming He assume it to be. Indeed, the increasingly powerful temptation to resort to it should be resisted. Moreover, judges are not well suited to supervise criminal investigations, a process which is generally best left to the executive branch.