People who are on probation have to agree to abide by a number of rules. If they fail to do so, their probation may be revoked. These rules and conditions vary from state to state. Most states do not allow probationers to possess firearms. They also must not commit any other offense during their time on probation. Some of the rules are imposed based on the type of crime that the probationer committed. For example, someone involved in a drug offense may be ordered to complete a rehabilitation program. Probationers may be required to undergo electronic monitoring. In all cases, probationers must check in with a probation officer on a regular basis.