Note: This article has been updated to reflect the law as of 2020.

The principal rule in regards to felony sentencing in Illinois courts is that the judge is not allowed to Sentence the Defendant to a conviction only. Rather, the law requires that the judge must sentence the defendant to a conviction combined with some other terms.

Usually in felony cases, the judge has discretion to sentence the defendant to prison, period imprisonment (such as work release), county jail, or some type of monitored sentence. The defendant would be monitored under a sentence of conditional discharge or Probation.

Illinois statutes allow the judge to sentence the defendant to intensive probation as well. As the term suggests, intensive probation is much more onerous than ordinary probation. Intensive probation requires more frequent reporting to a probation officer, more counseling and treatment, and more frequent drug testing.

Probation for a felony offense can last for years. Generally, the following rules apply to sentencing:

On Class 1 and Class 2 felony offenses the judge is authorized to sentence the defendant to a term of probation of up to four years. This is 48 months. (Class X felonies are nonprobationable.)

On lesser Illinois felony classes, such as Class 3 and Class 4 felonies, the court may sentence the defendant to a term of probation of 2 and 1/2 years (30 months).

There are additional rules concerning felony probation that should be considered. For example, the judge is allowed since the defendant to jail and probation at the same time. It should be noted that the defendant is entitled to receive credit for every day in custody prior to the finding of guilt. Also, any jail sentence is governed by the County Jail Good Behavior Allowance Act (730 ILCS 130/1 et seq). This law provides that in all jail sentences, the defendant receives good time credit. This means that whatever number is on paper, e.g. the sentencing order, the defendant serves 50 percent of that time. See 730 ILCS 130/3.

Illinois law requires that if a person is found guilty of sex offense, in order to receive probation, he must undergo a sex offender evaluation and consent to treatment. The court is not authorized under the law to send offenders to probation for a sex offense without these conditions being met.

Any sentence of prison would be served in the state penitentiary. The term of years in the penitentiary is dependent on the offense. For example, the Class 4 felony is sentencing range 1 to 3 years. Only when the defendant is extendable can the court exceed 3 years. As a practical matter, extended term sentencing is rare, but it does happen.

It should be noted that even if the court sentenced the defendant to prison, the judge can make the defendant serve a term of probation after his release from the penitentiary. This seldom happens, but in sex offenses, it is likely.