Brad Schlesinger at Outside the Beltway with a cogent take on how mandatory minimum sentences give too much power in justice to prosecutors and help kill trial by jury.
The heart of the matter:
By passing laws with fixed-minimum sentences for almost all crimes, legislatures, beginning largely in the 1980?s, removed discretion over offender sentencing from judges and handed prosecutors the power to determine which sentence a defendant will receive. Judges have no power to override the mandatory prison terms these laws carry, regardless of the individual circumstances of each case. This is especially troubling because of the overly punitive penalties these laws carry. Even worse, when a case does goes to trial, the jury doesn't even know how much time a defendant faces.
The prosecutor alone chooses whether to charge the accused, which charges to file, whether to drop charges, and whether or not a plea on lesser charges will be offered, outside of any judicial oversight. These unilateral discretionary decisions "often predetermine the outcome of a case since the sentencing judge has little, if any, discretion in determining the length, nature, and severity of the sentence." This results in radically different sentencing outcomes between the sentence a defendant receives who loses at trial compared to one who pleads guilty.
These enormously different outcomes effectively coerce criminal defendants into pleading guilty. Mandatory minimum sentencing laws give prosecutors the leverage and superior bargaining position needed to coax accused citizens, many of whom are completely innocent, into surrendering a fundamental right for a perceived benefit– a significantly lesser sentence for forgoing a jury trial and pleading guilty.
If that dynamic makes you mad, you might want to look into Families Against Mandatory Minimums.