Article VI. Appeals in Criminal Cases, Post-Conviction Cases, and Juvenile Court Proceedings · Not amended since adoption on record · Last verified July 20, 2026
In one sentenceRule 615 tells a reviewing court to ignore errors that don’t affect substantial rights, lets it notice plain errors even when no one objected at trial, and lists the remedies it can order once the appeal is decided.
(a)Insubstantial and Substantial Errors on Appeal. Any error, defect, irregularity, or
variance which does not affect substantial rights shall be disregarded. Plain errors or defects affecting substantial rights may be noticed although they were not brought to the attention of the trial court.
(b)Powers of the Reviewing Court. On appeal the reviewing court may:
(1)reverse, affirm, or modify the judgment or order from which the appeal is taken;
(2)set aside, affirm, or modify any or all of the proceedings subsequent to or dependent
upon the judgment or order from which the appeal is taken;
(3)reduce the degree of the offense of which the appellant was convicted;
(4)reduce the punishment imposed by the trial court; or
(5)order a new trial.
Plain-English Summary
Not every mistake at trial gets a defendant a new trial. Rule 615(a) tells a reviewing court to disregard any error, defect, irregularity, or variance that doesn’t affect substantial rights. But it also opens a door for errors that do — plain errors affecting substantial rights can be noticed on appeal even if trial counsel never raised them below.
Once the reviewing court reaches a decision, paragraph (b) lists what it can do: reverse, affirm, or modify the judgment; set aside, affirm, or modify related proceedings; reduce the degree of the offense; reduce the punishment; or order a new trial. A reversal doesn’t automatically mean starting over — the court can instead adjust the offense or the sentence itself.
Frequently Asked Questions
What is the plain-error doctrine under Rule 615?
It lets a reviewing court consider a clear error affecting a defendant’s substantial rights even when trial counsel never objected to it.
Does every mistake at trial require reversal?
No — an error that doesn’t affect substantial rights is disregarded.
Can the Appellate Court change the offense a defendant was convicted of?
Yes, reducing the degree of the offense is one of the remedies the rule lists.
Can a reviewing court lower a sentence instead of ordering a new trial?
Yes, reducing the punishment imposed is listed as a separate option.
Does Rule 615 require a new trial for every reversal?
No — the court can affirm, modify, reduce the offense or punishment, or order a new trial, depending on the case.
Committee Comments
This is section 121-9 of the Code of Criminal Procedure of 1963 without change in substance.
Source & verification. Rule text, official Committee Comments, and
amendment history are reproduced verbatim from the Illinois Supreme Court Rules,
promulgated by the Supreme Court of Illinois. Last verified July 20, 2026.
· Official source
Also known as:plain error rule Illinois criminal appealharmless error criminal appealreviewing court powers on appealplain error doctrine Illinois