Appeal from the Circuit Court of McHenry County. No. 02-JA-15. Honorable Gordon E. Graham and John D. Bolger, Judges, Presiding.
 The opinion of the court was delivered by: Justice Grometer
 Respondent, Lisa Z., appeals a series of orders of the circuit court of McHenry County declaring her an unfit parent and determining that it was in the best interests of her child, Amanda D., that her parental rights be terminated. The sole basis of the finding of unfitness was that respondent was previously convicted of aggravated battery of a child, as specified in section 1(D)(q) of the Adoption Act (Act) (750 ILCS 50/1(D)(q) (West 2002)). Because we hold section 1(D)(q) of the Act unconstitutional, we reverse the finding of unfitness and vacate the trial court's order terminating respondent's parental rights, as it was not preceded by a valid finding of unfitness (see In re J.W., 187 Ill. App. 3d 988, 999 (1989) ("A finding of unfitness is a prerequisite to addressing the question of the child's best interest")). We remand this cause for further proceedings consistent with the views expressed herein.
 On March 17, 1997, respondent pleaded guilty to a charge of aggravated battery (720 ILCS 5/12--4(a) (West 1996)). The victim of the battery was one of respondent's daughters, who is not involved in the instant case. According to the indictment in that case, respondent "knowingly caused great bodily harm to [her daughter], in that she fractured her arm."
 On December 3, 2000, Amanda was born. The State filed a petition for adjudication of wardship on September 3, 2002, alleging, inter alia, that Amanda was abused and neglected because respondent left the child with respondent's paramour for two days while she went to Chicago to use drugs; she used crack cocaine in front of Amanda; she suffered from depression and was not taking her prescribed medications on a regular basis; and she had yet to complete a recommended substance abuse program. On December 26, 2002, the trial court found that the State had proven the allegations set forth in the petition.
 On January 30, 2003, the State filed a petition for termination of parental rights. The sole allegation regarding respondent's unfitness to be a parent was that respondent previously had been convicted of aggravated battery to a child. On the same date, the State moved for summary judgment and attached to the motion a certified copy of respondent's conviction. The trial court granted the motion on February 25, 2003. Subsequently, a best-interests hearing was held, and, on November 25, 2003, the trial court terminated respondent's parental rights. Respondent now appeals.
 Respondent raises a number of issues on appeal, attacking section 1(D)(q) of the Act (750 ILCS 50/1(D)(q) (West 2002)), as well as certain aspects of the proceedings and the trial court's ultimate decision. As to section 1(D)(q), she argues that it violates the due process and equal protection guarantees of both the state and federal constitutions. U.S. Const., amend. XIV; Ill. Const. 1970, art. I, §2. We hold that section 1(D)(q) denies respondent due process, and we therefore need not address her other arguments.
 Statutes are presumed constitutional. Vuagniaux v. Department of Professional Regulation, 208 Ill. 2d 173, 193 (2003). The party challenging the statute bears the burden of establishing its invalidity. People ex rel. Lumpkin v. Cassidy, 184 Ill. 2d 117, 123 (1998). If reasonably possible, a court must affirm the statute's validity. People v. Jeffries, 164 Ill. 2d 104, 111 (1995). The constitutionality of a statute is a question of law, subject to de novo review. Brown's Furniture, Inc. v. Wagner, 171 Ill. 2d 410, 420 (1996).
 Respondent contends that section 1(D)(q) denies her due process. The statute states, in pertinent part:
 "D. 'Unfit person' means any person whom the court shall find to be unfit to have a child, without regard to the likelihood that the child will be placed for adoption. The grounds of unfitness are any one or more of the following, except that a person shall not be considered an unfit person for the sole reason that the person has relinquished a child in accordance with the Abandoned Newborn Infant Protection Act:
 (q) The parent has been criminally convicted of aggravated battery, heinous battery, or attempted murder of any child." 750 ILCS 50/1(D)(q) (West 2002).
 Respondent contends that section 1(D)(q) is unconstitutional in that it mandates a finding of unfitness based on the sole fact that she was convicted of aggravated battery to a child and it does not allow for the introduction of evidence of fitness, rehabilitation, or change in circumstance.
 Respondent's analysis of the due process issue mixes elements of both substantive and procedural due process. She cites In re M.H., 196 Ill. 2d 356 (2001), for the proposition that a parent's interest in raising his or her children is entitled to heightened protection. Thus, she argues that section 1(D)(q) must be narrowly tailored to advance a compelling state interest. These are hallmarks of a substantive due process analysis. See, e.g., Reno v. Flores, 507 U.S. 292, 301-02, 123 L.Ed. 2d 1, 16, 113 S.Ct. 1439, 1447 (1993). However, respondent later cites Mathews v. Eldridge, 424 U.S. 319, 335, 47 L.Ed. 2d 18, 33, 96 S.Ct. 893, 903 (1976), the seminal case in which the Supreme Court set forth the test for determining whether state action comports with procedural due process, and argues that section 1(D)(q) fails to satisfy the second prong of Mathews.
 Respondent's confusion is understandable. The issues are sometimes intermingled in case law. See, e.g., In re J.B., 328 Ill. App. 3d 175, 187-91 (2002) (citing Mathews, discussing substantive due process, and concluding that the procedures set forth in the Act ...