A probation revocation hearing occurs when someone serving a probation sentence violates the terms of the probation, according to Nolo. This hearing determines if the probationer violated the terms of probation. In some cases, it's also when a sentence is issued if the probationer did violate the probation terms.
While a probation revocation hearing is a court procedure to determine guilt or innocence, it isn't one that is heard before a jury. Instead, the prosecution presents a case directly to the judge. The probationer can present a defense, usually with the help of an attorney. The judge then decides if the probation terms were violated. This isn't based on a theory of "beyond a reasonable doubt" like other criminal law proceedings. Instead, it is based on a theory of "more likely than not" or "a preponderance of the evidence," according to FindLaw.
If the probationer is found guilty, the judge can then hand down a sentence. For minor violations, the court might order additional time on probation or order new probation terms. For more serious violations or for repeat probation violations, the court can revoke the probation. When that occurs, the probationer must serve out any prison term or other suspended sentences that were handed down when the person was found or pleaded guilty to the original crime. If the probation violation resulted in a new criminal charge, the probationer will go through the criminal justice system to answer to those charges.