delivered the opinion of the court:
The State and the defendant, Robert Pinkonsly, both appeal a decision of the appellate court affirming in part and vacating in part a McHenry County circuit court order dismissing the defendant’s amended petition under section 2 — 1401 of the Code of Civil Procedure (735 ILCS 5/2 — 1401 (West 2002)). Because the appellate court erred in vacating the defendant’s unlawful delivery of a controlled substance convictions and sentences and in not vacating the extended-term sentence on his narcotics racketeering conviction, we reverse.
BACKGROUND
On December 4, 1989, the defendant sold 27.2 grams of cocaine to an undercover police officer. Again, on December 6, 1989, the defendant sold 53.3 grams of cocaine to the officer. Finally, on December 12, 1989, the defendant sold 124.1 grams of cocaine to the officer. The defendant was arrested during this last sale. He was later indicted on one count of delivery of between 15 and 100 grams of a controlled substance (see Ill. Rev. Stat. 1989, ch. 561/2, par. 1401(a)(2)(A), currently codified at 720 ILCS 570/401(a)(2)(A) (West 2002)), one count of delivery of between 100 and 400 grams of a controlled substance (see Ill. Rev. Stat. 1989, ch. 56V2, par. 1401(a)(2)(B), currently codified as 720 ILCS 570/401(a)(2)(B) (West 2002)), and one count of narcotics racketeering (see Ill. Rev. Stat. 1989, ch. 56V2, par. 1654(a), currently codified at 725 ILCS 175/4(a) (West 2002)). The unlawful delivery offenses were Class X felonies; the narcotics racketeering offense was a Class 1 felony.
On August 23, 1991, the defendant was convicted on all three counts. At sentencing, the State asked the trial court to sentence the defendant to two concurrent 60-year, extended-term sentences on the delivery convictions and a consecutive 15-year sentence on the narcotics racketeering conviction. Defense counsel objected that “[tjhere have been no necessary findings or evidence to indicate extended terms.” The court sentenced the defendant to two concurrent 30-year sentences on the delivery convictions and another concurrent 30-year, extended-term sentence on the narcotics racketeering conviction. The defendant appealed, raising the sole issue of a purported speedy-trial violation. The appellate court affirmed. See People v. Pinkonsly, No. 2 — 91—1093 (1993) (unpublished order under Supreme Court Rule 23).
More than six years after his conviction, on December 17, 1997, the defendant filed a pro se “Petition for Relief from Judgment” under section 2 — 1401 of the Code of Civil Procedure. The defendant asserted that his trial attorney was ineffective for failing to file a motion to reduce the defendant’s sentence for narcotics racketeering and a motion to vacate the defendant’s unlawful delivery convictions as lesser-included offenses of narcotics racketeering. The trial court appointed an attorney for the defendant, and this new attorney filed an “AMENDED PETITION TO REDUCE SENTENCE,” arguing only that the length of the defendant’s sentence was excessive in light of his age. The State did not respond to this petition, and the trial court dismissed it.
The defendant appealed, and the appellate court appointed another attorney for the defendant. On appeal, the defendant contended that all of his prior attorneys, including his court-appointed attorney on his section 2 — 1401 petition, were constitutionally ineffective because they failed to challenge his extended-term sentence for narcotics racketeering, and they failed to attack his unlawful delivery convictions as lesser-included offenses of narcotics racketeering. The appellate court ordered supplemental briefing on two issues: (1) whether narcotics racketeering and unlawful delivery are based on the same physical act; and (2) whether People v. Callaway, 185 Ill. App. 3d 136 (1989), which held that Class 1, 2, and 3 felony unlawful delivery convictions were lesser-included offenses of narcotics racketeering, a Class 1 felony, applied here.
The appellate court, with one justice dissenting, affirmed in part and vacated in part. 331 Ill. App. 3d 984. The court rejected the State’s argument that the defendant’s section 2 — 1401 petition was untimely, because the State did not present that argument to the trial court. 331 Ill. App. 3d at 986. The court then declined to consider the defendant’s ineffective-assistance claims regarding his trial and appellate attorneys, reasoning that such claims are not cognizable in a section 2 — 1401 petition. 331 Ill. App. 3d at 986-87. The court, however, addressed the defendant’s argument that his attorney on his section 2 — 1401 petition was ineffective for failing to raise the issue of whether unlawful delivery was a lesser-included offense of narcotics racketeering. 331 Ill. App. 3d at 987. The court recited the familiar, two-prong Strickland v. Washington, 466 U.S. 668, 80 L. Ed. 2d 674, 104 S. Ct. 2052 (1984), standard for analyzing sixth amendment ineffective-assistance claims and reviewed Illinois law on lesser-included offenses. 331 Ill. App. 3d at 987-88. The court examined the charges against the defendant:
“The narcotics racketeering count contained an allegation that defendant participated in a pattern of narcotics activity. That allegation necessarily implied that defendant committed two Class 2, 1, or X felonies under the Cannabis Control Act [citation] or the Illinois Controlled Substances Act. Counts I and II alleged that defendant committed two Class X felonies under the Illinois Controlled Substances Act. Accordingly, the statutory elements of narcotics racketeering were implicitly contained in the unlawful-delivery-of-cocaine counts, a fact that renders the unlawful-delivery-of-cocaine counts lesser-included offenses. See People v. Callaway, 185 Ill. App. 3d 136 (1989).’’ 331 Ill. App. 3d at 988.1
The court held that the defendant’s section 2 — 1401 attorney was ineffective for failing to raise this issue and vacated the defendant’s convictions and sentences on both delivery counts. 331 Ill. App. 3d at 989. The court further held that the defendant’s section 2 — 1401 attorney was not ineffective for failing to challenge the defendant’s extended-term sentence on his narcotics racketeering conviction. 331 Ill. App. 3d at 991. Though the trial court did not offer a basis for the extended-term sentence, the State mentioned at sentencing that the defendant had a prior Class 1 felony conviction for “possession with intent to deliver.” 331 Ill. App. 3d at 991.
The dissent initially noted that the majority opinion did not address the central issue in this case: whether predicate offenses are lesser-included offenses. 331 Ill. App. 3d at 991 (O’Malley, J., dissenting). After reviewing Garrett v. United States, 471 U.S. 773, 85 L. Ed. 2d 764, 105 S. Ct. 2407 (1985), where the United States Supreme Court expressed “serious doubts” that importing marijuana was a lesser-included offense of engaging in a continuing criminal enterprise, the dissent characterized the defendant’s conduct as “multilayered and not susceptible to the ‘classic relationship’ of lesser-included and greater offenses.” 331 Ill. App. 3d at 992. According to the dissent, the Class X delivery counts could not be lesser-included offenses of the Class 1 racketeering count:
“The General Assembly has chosen to make the delivery of between 15 and 100 grams of cocaine a Class X felony, while it has made the later-enacted narcotics racketeering a Class 1 felony. This scheme is indicative of the legislature’s intent to make large-scale drug delivery a more serious offense than the receipt of income from multiple, smaller drug offenses, rather than a lesser-included offense.” 331 Ill. App. 3d at 994.
We allowed the State’s petition for leave to appeal. 177 Ill. 2d R. 315(a).
ANALYSIS
In its appeal, the State raises three issues: (1) whether the appellate court erred in granting relief on the defendant’s section 2 — 1401 petition because it was untimely; (2) whether the appellate court erred in granting relief on the defendant’s petition because ineffective assistance of counsel claims are not cognizable in section 2 — 1401 proceedings; and (3) whether the appellate court erred in granting relief on the defendant’s petition because unlawful delivery of a controlled substance is not a lesser-included offense of narcotics racketeering. We review the trial court’s dismissal of the defendant’s section 2 — 1401 petition for an abuse of discretion. See People v. Haynes, 192 Ill. 2d 437, 461 (2000).
Section 2 — 1401 of the Code of Civil Procedure, formerly section 72 of the Civil Practice Act, provides a comprehensive statutory procedure by which final orders and judgments may be challenged more than 30 days after their entry. People v. Harvey, 196 Ill. 2d 444, 447 (2001) (stating that section 2 — 1401 provides a civil remedy, which also applies to criminal cases). A section 2 — 1401 petition filed more than two years after the challenged judgment cannot be considered absent a clear showing that the person seeking relief was under a legal disability or duress or the grounds for relief were fraudulently concealed. People v. Caballero, 179 Ill. 2d 205, 210-11 (1997); see 735 ILCS 5/2 — 1401(c) (West 2002). If the party opposing the section 2 — 1401 petition does not raise the limitations period as a defense, it may be waived. See Harvey, 196 Ill. 2d at 447.
The defendant was convicted on August 23, 1991, but he did not file his pro se section 2 — 1401 petition until October 17, 1997, well beyond the two-year limitations period. The State did not raise the timeliness issue before the trial court, though it did raise that issue in answering the defendant’s appeal. The State refers us to the “well-established rule” that a prevailing party may raise issues on appeal that were not raised at trial.
We agree with the State that, generally, an appellee may raise any arguments in support of the trial court’s judgment, even though they were not raised before the trial court, provided they have a sufficient factual basis before the trial court. See People v. Monroe, 118 Ill. 2d 298, 300 (1987); see also People v. Schott, 145 Ill. 2d 188, 201 (1991). However, in People v. Wright, 189 Ill. 2d 1 (1999), we addressed a similar argument from the State in the context of a petition under the Post-Conviction Hearing Act (725 ILCS 5/122 — 1 et seq. (West 1994)) and declined to apply this exception to the waiver rule. In Wright, the State argued on appeal that the defendant’s postconviction petition was untimely because he filed it more than six months after the denial of his motion to reconsider the denial of his certiorari petition to the United States Supreme Court. The defendant responded that the State had waived its limitations period argument by failing to raise it before the trial court. The State relied upon this exception. We stated:
“Here, although the facts support the conclusion that defendant did not file his petition within the time limits found in section 122 — 1, that section allows a defendant to file a petition outside the limitations period if the late filing is not due to the defendant’s culpable negligence. [Citation.] By not raising this issue until the cause was on appeal, the State has effectively precluded defendant from seeking to amend his petition to allege facts demonstrating that the late filing was not caused by his culpable negligence. While we recognize that section 122 — 1 requires the defendant to allege the facts demonstrating a lack of culpable negligence, we do not believe that this requirement allows the State to wait until an appeal to raise an affirmative defense that the defendant may be able to avoid by amending his petition. By failing to raise this issue below, the State has waived its right to argue that the defendant’s petition is untimely.” Wright, 189 Ill. 2d at 11. Just as the Post-Conviction Hearing Act has an excep-
tion to its limitations period for delays not attributable to the defendant’s culpable negligence (see 725 ILCS 5/122 — 1(c) (West 2002)), section 2 — 1401 has an exception to its limitations period for delays attributable to disability, duress, or fraudulent concealment (see 735 ILCS 5/2 — 1401(c) (“Time during which the person seeking relief is under legal disability or duress or the ground for relief is fraudulently concealed shall be excluded in computing the period of 2 years”)). We conclude that our statement in Wright applies with equal force here. If the State wished to argue that the defendant’s section 2 — 1401 petition was untimely, it should have done so before the trial court, where any amendments could have been made and any factual disputes could have been resolved. Wright, 189 Ill. 2d at 12. The State waived its timeliness argument. We turn to the propriety of the defendant’s section 2 — 1401 petition.
In a legal memorandum supporting his pro se section 2 — 1401 petition, the defendant claimed, inter alia, that he was deprived of “his Fifth Amendment Right to be protected from conviction and multiple punishments for the same conduct” because he was convicted and sentenced for both unlawful delivery and narcotics racketeering. Before the appellate court, the defendant dropped this constitutional characterization of the issue and simply argued that the delivery convictions were lesser-included offenses of the narcotics racketeering conviction under the so-called charging instrument approach and, accordingly, they should be vacated. Here, the State argues that the charging instrument approach subverts the legislature’s intent that narcotics racketeering supplement existing drug trafficking sanctions.
This issue is still essentially a constitutional issue. The prohibition against double jeopardy (see U.S. Const., amends. Y, XTV; Ill. Const. 1970, art. I, § 10; see also 720 ILCS 5/3 — 4 (West 2002)) safeguards against multiple punishments for the same offense (see North Carolina v. Pearce, 395 U.S. 711, 717, 23 L. Ed. 2d 656, 664-65, 89 S. Ct. 2072, 2076 (1969); People v. Totten, 118 Ill. 2d 124, 130-31 (1987)) and consequently bars prosecution for both an offense and a lesser-included offense (see Brown v. Ohio, 432 U.S. 161, 53 L. Ed. 2d 187, 97 S. Ct. 2221 (1977); People v. Washington, 272 Ill. App. 3d 913, 920 (1995); see generally People v. King, 66 Ill. 2d 551, 566 (1977)). However, we decline to reach this issue. Though the parties dispute the application of the charging instrument approach, neither party has squarely addressed double jeopardy in this appeal. Additionally, we will not consider a constitutional issue if we can decide the case on other grounds. See Bonaguro v. County Officers Election Board, 158 Ill. 2d 391, 396 (1994); In re Estate of Ersch, 29 Ill. 2d 572, 576-77 (1963) (“It is the established rule of this court that a constitutional question will not be considered if the case can be decided without doing so”).
To obtain relief under section 2 — 1401, the defendant “must affirmatively set forth specific factual allegations supporting each of the following elements: (1) the existence of a meritorious defense or claim; (2) due diligence in presenting this defense or claim to the circuit court in the original action; and (3) due diligence in filing the section 2 — 1401 petition for relief.” Smith v. Airoom, Inc., 114 Ill. 2d 209, 220-21 (1986); accord Kaput v. Hoey, 124 Ill. 2d 370, 378 (1988). That is, in order to obtain relief under section 2 — 1401, the defendant must show both a meritorious defense to the charges against him and due diligence in presenting it.
A meritorious defense under section 2 — 1401 involves errors of fact, not law. See Haynes, 192 Ill. 2d at 461; see also Burns v. People, 9 Ill. 2d 477, 480 (1956) (noting that a section 72 motion “is not available for the purpose of correcting errors at law” such as ineffective assistance of counsel). As we have stated:
“A section 2 — 1401 petition for relief from a final judgment is the forum in a criminal case in which to correct all errors of fact occurring in the prosecution of a cause, unknown to the petitioner and court at the time judgment was entered, which, if then known, would have prevented its rendition. [Citations.] A section 2 — 1401 petition, however, is ‘not designed to provide a general review of all trial errors nor to substitute for direct appeal.’ ” Haynes, 192 Ill. 2d at 461, quoting People v. Berland, 74 Ill. 2d 286, 314 (1978).
For this reason, a section 2 — 1401 petition differs from a postconviction petition. A postconviction petition requires the court to decide whether the defendant’s constitutional rights were violated at trial (see 725 ILCS 5/122 — 1(a) (West 2002)); a section 2 — 1401 petition, on the other hand, requires the court to determine whether facts exist that were unknown to the court at the time of trial and would have prevented entry of the judgment. See People v. Hayden, 288 Ill. App. 3d 1076, 1078 (1997). The defendant does not argue that the trial court should have considered his section 2 — 1401 petition as a post-conviction petition. See People ex rel. Palmer v. Twomey, 53 Ill. 2d 479, 484 (1973); People v. Gandy, 227 Ill. App. 3d 112, 139 (1992) (“Where the section 2 — 1401 petition is prepared pro se and alleges a deprivation of constitutional rights cognizable under the Post-Conviction Hearing Act, the trial court is to treat it as such”). Such an argument would fail because, although his initial petition was pro se, his amended petition, which is the subject of this appeal, was prepared by an attorney and clearly brought under section 2 — 1401. See People v. Phelps, 51 Ill. 2d 35, 38 (1972) (holding that where an amended postconviction petition filed by appointed counsel did not include allegations from the defendant’s pro se postconviction petition, such issues were not before the court); cf. Barnett v. Zion Park District, 171 Ill. 2d 378, 384 (1996) (“Where an amended pleading is complete in itself and does not refer to or adopt the prior pleading, the earlier pleading ceases to be part of the record for most purposes and is effectively abandoned and withdrawn”).
We have long held that section 2 — 1401 proceedings are not an appropriate forum for ineffective-assistance claims because such claims do not challenge the factual basis for the judgment. See People v. Anderson, 31 Ill. 2d 262, 264 (1964); accord People v. Smith, 176 Ill. App. 3d 132, 136 (1988). The appellate court here correctly refused to disturb the ruling of the trial court denying relief to the defendant on his claims that his trial and appeal attorneys were ineffective. Before the appellate court, the defendant also asserted that his section 2 — 1401 attorney was ineffective for failing to raise the lesser-included offense issue. That court agreed with the defendant. The State now contends that the defendant was not entitled to effective assistance of counsel in the section 2 — 1401 proceeding.
The right to assistance of counsel at trial is derived from the sixth amendment, but the right to assistance of counsel in collateral postconviction proceedings is a matter of legislative grace. People v. Owens, 139 Ill. 2d 351, 364 (1990); People v. Porter, 122 Ill. 2d 64, 73 (1988). A defendant may not properly assert a constitutional claim of ineffective assistance of postconviction counsel (see People v. Davis, 156 Ill. 2d 149, 159 (1993)) because a postconviction petitioner is guaranteed only the level of assistance provided by the Post-Conviction Hearing Act. See People v. Flores, 153 Ill. 2d 264, 276 (1992); see also People v. Wright, 149 Ill. 2d 36, 64 (1992) (postconviction petitioners are guaranteed a “reasonable” level of assistance); 134 Ill. 2d R. 651(c).
“This distinction is rational, because trial counsel plays a different role than counsel in post-conviction proceedings. [Citation.] At trial, counsel acts as a shield to protect defendants from being ‘haled into court’ by the State and stripped of their presumption of innocence. [Citation.] Post-conviction petitioners, however, have already been stripped of the presumption of innocence, and have generally failed to obtain relief on appellate review of their convictions. *** Counsel are appointed to represent post-conviction petitioners, not to protect them from the prosecutorial forces of the State, but to shape their complaints into the proper legal form and to present those complaints to the court.” Owens, 139 Ill. 2d at 364-65.
The defendant here is not a postconviction petitioner, but instead a section 2 — 1401 petitioner. Section 2 — 1401 does not specify any level of assistance, and the appellate court erroneously applied the Strickland standard to the defendant’s claim that his section 2 — 1401 attorney was ineffective. Assuming that the defendant was entitled to the same level of assistance on his section 2 — 1401 petition as on a postconviction petition, the defendant did not receive unreasonable assistance. The defendant’s attorney was not unreasonable for failing to raise a putative legal error in a proceeding where only fact errors are cognizable. See People v. Landwer, 166 Ill. 2d 475, 486 (1995) (“Whether a charged offense encompasses an included offense is a matter of law”). The appellate court erred in vacating the defendant’s unlawful delivery convictions and sentences.
In his cross-appeal, the defendant raises one issue: whether the appellate court erred in refusing to grant relief on his claim that an extended-term sentence for narcotics racketeering was improper.
The Unified Code of Corrections allows an extended term sentence only “for the class of the most serious offense of which the offender was convicted.” Ill. Rev. Stat. 1989, ch. 38, par. 1005 — 8—2(a), currently codified as 730 ILCS 5/5 — 8—2(a) (West 2002). At sentencing, the defendant stood convicted of two counts of unlawful delivery, both Class X felonies, and one count of narcotics racketeering, a Class 1 felony. Thus, the defendant could have received an extended-term sentence only on the delivery convictions. The State concedes that “if this Court reverses the appellate court decision on the Class X offenses, narcotics racketeering is not the highest statutory class of offenses for which Defendant was convicted.”
Because the appellate court erred in vacating the defendant’s unlawful delivery convictions, it also erred in refusing to vacate the sentence on his narcotics racketeering conviction. See People v. Arna, 168 Ill. 2d 107, 113 (1995) (“A sentence which does not conform to a statutory requirement is void”). In the exercise of our supervisory authority, we impose a 15-year sentence on the defendant’s narcotics racketeering conviction (see 730 ILCS 5/5 — 8—1(a)(4) (West 2002)), to run concurrently with his 30-year sentences on the delivery convictions. See 134 Ill. 2d R. 615(b)(4) (“On appeal the reviewing court may *** reduce the punishment imposed by the trial court”).
CONCLUSION
For the reasons that we have discussed, we reverse the judgment of the appellate court and affirm the judgment of the circuit court as modified.
Appellate court judgment reversed; circuit court judgment affirmed as modified.
The appellate court here also cited People v. Smith, 295 Ill. App. 3d 405 (1998), parenthetically noting that “the Appellate Court, Fifth District, vacated a Class X possession of a controlled substance (cocaine) with intent to deliver, stating that it was a lesser-included offense of narcotics racketeering.” 331 Ill. App. 3d at 989. Our review of Smith reveals such a holding, but only in material designated as unpublishable under Supreme Court Rule 23. That holding, accordingly, had no precedential value and should not have been relied upon by the appellate court. See 166 Ill. 2d R. 23(e) (“An unpublished order of the court is not precedential and may not be cited by any party except to support contentions of double jeopardy, res judicata, collateral estoppel or law of the case”); Baker v. Hutson, 333 Ill. App. 3d 486, 492 (2002); People v. Petty, 311 Ill. App. 3d 301, 303 (2000).