Limits on judicial discretion are a threat to the separation of powers. When the legislature interferes with the discretion of judges it inherently weakens the independence of the judicial branch. Although the recent recommendations by the sentencing commission deal with federal judges, the issue of judicial discretion has also arisen in states across the country. Judge Rose Bird, the first female Chief Justice of the California Supreme Court, laid out the argument for judicial discretion in a passionate dissent in People v Tanner, 24 Cal. 3d 514. Mandatory sentences for offenders, whether requirements or guidelines, takes discretion away from the judges that are expected to have the training and experience and places it instead in the hands of prosecutors who have the discretion in choosing the allegations. Judges are expected to be unbiased decision makers, while prosecutors have a vested interest in racking up convictions and longer sentences. Judges are expected to have greater experience than prosecutors, who in some cases may be relatively junior attorneys.
The recent recommendations from the sentencing commission are a step in the right direction. These recommendations allow judges to take more things into account when setting sentences. However the commission itself remains a legislative encroachment on judicial independence. That it has granted some discretion back to the judiciary does not change the fact that such discretion should never have been stripped away in the first place.
