Mandatory sentencing gives prosecutors undue power.  Prosecutors can stack charges, which they can use to scare a defendant into accepting a plea bargain. Prosecutors are part of the executive branch; they are directly answerable to elected officials (and are often elected themselves), whereas judges are generally more removed from political influence. Politicians often promote themselves as being “tough on crime.” [1] In order to make good on this claim, they may pressure prosecutors to increase conviction rates, get longer sentences, etc. Thus political pressure may lead prosecutors to handle cases in a way that makes them more popular with the public, rather than one which gives the criminal their fair due. Because judges are less susceptible to public pressure, it is safer to entrust discretion to them.  [1] Michael A. Simons, “Departing Ways: Uniformity, Disparity, and Cooperation in Federal Drug Sentences,” Villanova Law Review, Vol. 47, Issue 2, 2002, 923.