Defendants who are charged with violating their probation are exposed to any potential penalties that they faced in their underlying charge. For example, if you were on probation for a theft conviction which carried a maximum jail sentence of 1 year, the court could impose the 1 year jail sentence originally available to them, but no more. Most judges do impose some sort of punitive sanction, because they view the case as one in which the defendant has already had a chance and has failed.
The Role of the Prosecutor
The role of the prosecutor varies depending on your jurisdiction. Some district attorneys (DAs) take a very active role in probation violation cases, while others defer to the probation officer supervising the defendant. In either case, defense attorneys are able to represent people charged with violation of probation, and are able to negotiate with the DA or the probation officer to lessen the sentence. If the parties agree on a stipulated sentence for the violation, the judge is bound to accept that agreement.
The Role of the Judge
The judge is the ultimate trier of facts on a complaint for violation of probation. You are entitled to a testimonial hearing, which means that at least one witness, generally the probation officer, is required to testify under oath about the basis of the revocation complaint. The defendant is allowed to put on their own witnesses to attempt to show why the complaint is untrue. You do not have the right to a jury trial on a complaint for revocation of probation. The trial judge hears the testimony and decides if probation has been violated. If the judge determines that a violation occurred, or if a defendant admits to a violation, the judge imposes the new sentence. This can be as simple as revoking and reinstating probation without any additional consequences, it can involve additional jail time and/or condition then another period of probation, or it can include a jail sentence and termination of the case without additional probation. Which route the judge opts for depends upon any statements or agreements from the parties to the case and the specific facts of the case. Ultimately, the defendant almost always fares better in these cases when they are represented by competent counsel.