Mandatory Minimum Sentences.

Used to be, back in the 60's and 70's, judges had broad discretion in sentences.  Unfortunately a number of judges abused this discretion, letting criminals off with slap-on-the-wrist sentences when the community wanted the throw the book at them. 
  As a result, in the 70's and 80's, Congress and state legislatures  passed laws requiring judges to impose mandatory minimum sentences in all cases, mitigating circumstances be damned.  Judges have been whining about this ever since.  But the mandatory minimum sentencing laws still mostly stand, the voters have little interest in the whines of judges.