People who have been found guilty of a crime are often placed on probation, either right after conviction and sentencing or after they are released from jail or prison. A person who is on probation by does not comply may be subject to a probation violation hearing.
At a probation violation hearing, the person is at risk of having any unsuspended time revoked for failure to comply with probation. At the hearing the probation officer will inform the court, either by letter or in person, about every single thing that a person did during their probation time. If a person misses a meeting or has a dirty drug screen they may not be violated for it, but if they are violated later, then every thing they did wrong during probation can be brought up. To make matters more difficult, since the probation violation hearing is not a trial, the Judge can consider evidence that he would normally not be able to, such as hearsay testimony or letters from people not present in the courtroom.
A person can only be sentenced to serve additional time if they have suspended time from a previous conviction and if they are still within their good behavior period imposed by the judge when they were originally convicted and sentenced.