Colorado Rule 35(a) Illegal Sentence Motions
Not every sentencing problem is an appeal issue. Some sentences are simply not authorized by Colorado law, and Crim. P. 35(a) exists to fix them. This page explains what counts as an illegal sentence, the difference between a sentence that is illegal and a sentence that was imposed in an illegal manner, when each can be challenged, and how these motions are litigated and reviewed.
What Rule 35(a) does
Crim. P. 35(a) allows a court to correct a sentence that was not authorized by law, or that was imposed without jurisdiction, at any time. There is no statute of limitations on an illegal sentence. A separate part of the same rule addresses a sentence that was imposed in an illegal manner — the sentence itself is lawful, but the procedure used to reach it was not — and that kind of claim must be raised within the shorter period the rule allows for sentence reduction.
The distinction matters enormously in practice. "This sentence exceeds what the statute permits" can be raised years later. "The court did not follow the correct procedure at my sentencing hearing" usually cannot.
What counts as an illegal sentence?
An illegal sentence is one the court had no legal authority to impose. Recurring examples in Colorado practice include:
- A prison term above or below the range authorized for the offense and the findings actually made.
- An incorrect period of mandatory parole, or parole imposed when it should not have been, or omitted when it was required.
- Consecutive sentences where the law required concurrent terms, or the reverse.
- Sentences that violate double jeopardy because convictions should have merged.
- Errors in habitual criminal or crime-of-violence sentence enhancement.
- Errors in indeterminate sentencing under the Colorado Sex Offender Lifetime Supervision Act.
- Failure to award presentence confinement credit that the defendant was legally entitled to receive.
- Certain restitution orders that exceed statutory authority.
- A mittimus that does not match what the court actually pronounced.
Where the motion is filed and what happens next
A Rule 35(a) motion is filed in the district court that imposed the sentence, not in the Court of Appeals. Because the question is usually purely legal, the court can often resolve it on the pleadings and the existing record; an evidentiary hearing is generally unnecessary. The prosecution ordinarily responds, and the court either corrects the sentence, orders a resentencing hearing, or denies relief.
If the motion is denied, the denial can be appealed to the Colorado Court of Appeals in the same way as other postconviction orders, and the deadline for that appeal is short.
What standard applies on review?
The legality of a sentence is a question of law, so appellate courts review it de novo and give no deference to the district court's conclusion. That is a meaningful advantage compared with most sentencing challenges, which are reviewed only for abuse of discretion. It is also why the quality of the legal argument, and the accuracy of the statutory analysis, tends to decide these cases.
Can the court consider evidence outside the record?
Usually no, and usually it does not need to. A Rule 35(a) claim is normally proved from the face of the record: the charging document, the verdict or plea, the sentencing transcript, and the mittimus. That is different from a Rule 35(c) proceeding, where the whole point is often to develop facts that the record does not contain.
Rule 35(a), 35(b) and 35(c) compared
| 35(a) | 35(b) | 35(c) | |
|---|---|---|---|
| Purpose | Correct a sentence that is not authorized by law | Ask the court to reduce a lawful sentence | Vacate a conviction or sentence on constitutional grounds |
| Timing | Any time, for an illegal sentence | A short, fixed window after sentencing or after the appeal | Governed by the limits in section 16-5-402, C.R.S. |
| Discretion? | No — an illegal sentence must be corrected | Yes — entirely discretionary | No, if the claim is established |
| Hearing | Rarely needed | Rarely held | Often required |
A single case can involve more than one of these, and the sequencing matters. Filing the wrong motion first can waste the one realistic opportunity to get relief.
Why these cases are worth a second look
Illegal sentence issues are frequently missed, because they are technical, because they often turn on the interaction of two or three statutes, and because nobody re-reads the mittimus after the hearing ends. In my experience, a careful audit of the sentencing record and the mittimus is one of the highest-yield reviews available in a postconviction case — and one of the few that has no deadline.
Who reviews the record and writes the motion?
I do. I read the sentencing transcript and the mittimus myself, I run the statutory analysis myself, and I write the motion myself. If I do not think the sentence is illegal, I will tell you that directly rather than filing something that will not succeed.
For more on evaluating any appellate lawyer, see How to Choose a Colorado Criminal Appeals Attorney.
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Written by Tillman Patrick Clark, Tillman Patrick Clark, LLC, Denver, Colorado. Last reviewed: July 31, 2026. This page is general information about Colorado sentencing and postconviction procedure and is not legal advice. Rules, statutes and deadlines change; confirm current requirements with a lawyer about your specific case.