Because criminal defendants have no incentive to plead guilty as charged, and because the number of cases that would otherwise need to be tried vastly exceeds the resources available to try them, plea bargaining is first and foremost a strategy for avoiding total gridlock.
Plea bargaining is also a method of delivering leniency where it is actually appropriate. The criminal justice system is notoriously lenient towards first offenders of all kinds, and while I find this objectionable with respect to assaultive crimes and crimes against public safety, even I would agree that some leniency is in order for first offenders charged with property crimes, because the immediate effect of felony records is to make those individuals less employable and more likely to be a burden to all of us for the rest of their lives.
Plea bargaining is finally a means of salvaging some accountability for defendants whose cases have developed frailties often associated with the need to rely on the testimony of witnesses who are peers of defendants.
There are certainly advantages and disadvantages to plea bargaining. The advantages are that victims are spared either the trauma or inconvenience of testifying, according to the nature of the case, and the prosecution is spared the risk of acquittal, i.e., a conviction is guaranteed.
The concrete disadvantage is that there is some reduction in the conviction offense or sentence on both, although the outcomes of responsible plea bargaining are not dramatically different from probable outcomes absent plea bargaining. The most significant disadvantage of plea bargaining, however, is the abstract one –it involves negotiating with...