<prompt> Translate the following text to EnglishMkataba wa sheria za mahakama za jinai ulizinduliwa mwaka 1987 na sheria za mahakama za jimbo la California, na kwa hivyo, sheria hizo zilipunguza sana uhuru wa hakimu wa kuamua hukumu.  <response>: Proffers are increasingly common in the criminal justice system, especially since the enactment of federal sentencing guidelines in 1987, which substantially restricted a judges discretion in sentencing. 