CAVANAGH, J.
This case requires us to determine whether collateral estoppel may be applied to preclude review of a criminal defendant’s claim of ineffective assistance of counsel when a prior civil judgment held that defense counsel’s performance did not amount to malpractice. We hold that collateral estoppel may not be applied in these circumstances because defendant did not have a full and fair opportunity to litigate his ineffective-assistance-of-counsel claim, contrary to the requirements of the doctrine itself.
Given our conclusion that collateral estoppel is inapplicable, we must also determine whether defendant [43]*43was deprived of his right to the effective assistance of counsel under Strickland v Washington, 466 US 668; 104 S Ct 2052; 80 L Ed 2d 674 (1984). We hold that defense counsel’s performance was constitutionally deficient because she failed to exercise reasonable professional judgment when she decided to forgo any investigation of the case before settling on a defense strategy. That deficiency prejudiced defendant by undermining the reliability of the outcome of his trial, which rested solely on the credibility of the complainant and defendant. Accordingly, we reverse the judgment of the Court of Appeals and remand this case to the trial court for a new trial.
I. FACTS AND PROCEEDINGS
Defendant was charged with five counts of second-degree criminal sexual conduct (CSC-II) for allegedly touching the genitals of his eight-year-old daughter and forcing her to touch his genitals. During the bench trial, the complainant testified that defendant touched her three or four times (once or twice while she was in defendant’s bed at night) and would lower her hand to his genitals. Lilya Tetarly, the complainant’s mother and defendant’s ex-wife, testified that in 2004 the complainant developed yeast infections. On direct examination, Tetarly denied asking defendant to treat the yeast infections with ointment and stated that the complainant became upset when she had to go to defendant’s home. Defense counsel did not cross-examine Tetarly. As the only defense witness, defendant testified that he never forced the complainant to touch his genitals and that he touched the complainant’s genitals six times to apply medication at Tetarly’s insistence after a heated argument over whether it was appropriate for him to apply the ointment. Defendant [44]*44was convicted of three counts of CSC-II. Two counts were based on evidence that defendant touched the complainant and one count was based on evidence that defendant forced her to touch his genitals. After the parties’ closing arguments, the trial court commented that “very little’s clear to me in this case, starting with what the allegations are that go to each count.”
On direct appeal, defendant argued that defense counsel was ineffective for failing to impeach Tetarly with evidence of bias pertaining to their divorce four years earlier. Defendant argued that Tetarly had attempted to hit him with her car, which was supported by a police report, and assaulted him while he was driving, which resulted in Tetarly’s arrest on domestic violence charges. The Court of Appeals denied defendant’s motion for an evidentiary hearing pursuant to People v Ginther, 390 Mich 436; 212 NW2d 922 (1973),1 and held that defense counsel was not ineffective for failing to impeach Tetarly because the record lacked evidence to show that she was still upset over the divorce. People v Trakhtenberg, unpublished opinion per curiam of the Court of Appeals, issued March 27, 2007 (Docket No. 268416). Defendant applied for leave to appeal in this Court, which was denied. People v Trakhtenberg, 480 Mich 856 (2007).
Defendant subsequently filed a legal malpractice claim against defense counsel, which the trial court dismissed upon defense counsel’s motion for summary disposition. The Court of Appeals affirmed, holding that defense counsel’s performance fell within the “attorney [45]*45judgment rule.” Trakhtenberg v McKelvy, unpublished opinion per curiam of the Court of Appeals, issued October 27,2009 (Docket No. 285247).2 See, also, Simko v Blake, 448 Mich 648; 532 NW2d 842 (1995). Meanwhile, in his criminal case, defendant filed a motion for relief from judgment under MCR 6.508(D)(3), claiming that he was entitled to a new trial because he was denied the effective assistance of trial and appellate counsel and, alternatively, that newly discovered evidence warranted a new trial. The trial court denied the motion under MCR 6.508(D)(3)(b), and the Court of Appeals denied defendant leave to appeal. People v Trakhtenberg, unpublished order of the Court of Appeals, entered March 20, 2009 (Docket No. 290336). In lieu of granting leave to appeal, this Court retained jurisdiction and remanded the case to the Court of Appeals for consideration as on leave granted, and the Court of Appeals was ordered to remand the case to the trial court to conduct a Ginther hearing in order to evaluate defendant’s claims. People v Trakhtenberg, 485 Mich 1132 (2010).
During the course of the Ginther hearing, voluminous testimony was taken. Tetarly admitted that she was dissatisfied with the divorce judgment and had made negative comments about defendant in front of the complainant. And, for the first time, Tetarly disclosed that before reporting the complainant’s allegations of abuse to the authorities, she brought the complainant to a youth pastor. Tetarly stated that she then brought the complainant to CARE House, which provides intervention and treatment services for child victims of abuse, where Amy Allen, a CARE House [46]*46employee, performed a forensic interview, during which the complainant alleged the abuse. The responding detective’s police report states that the detective asked Tetarly to directly ask the complainant whether defendant had ever touched her “private parts” with his fingers. That questioning eventually led to the complainant’s second formal allegation of abuse.
Allen, who was unaware that the complainant had spoken to others about the abuse, testified that it is important to know whether the child has spoken to anyone else in order to conduct a proper forensic interview because, as a result of repeated interviewing, a child might start to mistakenly believe that something happened to him or her. Additionally, Dr. Katherine Okla, a clinical psychologist specializing in sexual abuse, noted her concern regarding the complainant’s knowledge of her mother’s hatred of defendant and explained that Tetarly’s leading and suggestive questions and the repeated questioning of the complainant (especially in a therapeutic rather than forensic setting) could have tainted the child’s recollection of the events surrounding the alleged abuse. Defendant testified that he had requested that defense counsel consult with numerous witnesses including Allen and HT, who was defendant’s son.
Defense counsel testified that her defense theory was two-fold: she would (1) impeach the complainant’s trial testimony with an inconsistent statement regarding the number of times defendant made her touch him and (2) show that defendant lacked the requisite intent of sexual gratification to be convicted of CSC-II.3 Addition[47]
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CAVANAGH, J.
This case requires us to determine whether collateral estoppel may be applied to preclude review of a criminal defendant’s claim of ineffective assistance of counsel when a prior civil judgment held that defense counsel’s performance did not amount to malpractice. We hold that collateral estoppel may not be applied in these circumstances because defendant did not have a full and fair opportunity to litigate his ineffective-assistance-of-counsel claim, contrary to the requirements of the doctrine itself.
Given our conclusion that collateral estoppel is inapplicable, we must also determine whether defendant [43]*43was deprived of his right to the effective assistance of counsel under Strickland v Washington, 466 US 668; 104 S Ct 2052; 80 L Ed 2d 674 (1984). We hold that defense counsel’s performance was constitutionally deficient because she failed to exercise reasonable professional judgment when she decided to forgo any investigation of the case before settling on a defense strategy. That deficiency prejudiced defendant by undermining the reliability of the outcome of his trial, which rested solely on the credibility of the complainant and defendant. Accordingly, we reverse the judgment of the Court of Appeals and remand this case to the trial court for a new trial.
I. FACTS AND PROCEEDINGS
Defendant was charged with five counts of second-degree criminal sexual conduct (CSC-II) for allegedly touching the genitals of his eight-year-old daughter and forcing her to touch his genitals. During the bench trial, the complainant testified that defendant touched her three or four times (once or twice while she was in defendant’s bed at night) and would lower her hand to his genitals. Lilya Tetarly, the complainant’s mother and defendant’s ex-wife, testified that in 2004 the complainant developed yeast infections. On direct examination, Tetarly denied asking defendant to treat the yeast infections with ointment and stated that the complainant became upset when she had to go to defendant’s home. Defense counsel did not cross-examine Tetarly. As the only defense witness, defendant testified that he never forced the complainant to touch his genitals and that he touched the complainant’s genitals six times to apply medication at Tetarly’s insistence after a heated argument over whether it was appropriate for him to apply the ointment. Defendant [44]*44was convicted of three counts of CSC-II. Two counts were based on evidence that defendant touched the complainant and one count was based on evidence that defendant forced her to touch his genitals. After the parties’ closing arguments, the trial court commented that “very little’s clear to me in this case, starting with what the allegations are that go to each count.”
On direct appeal, defendant argued that defense counsel was ineffective for failing to impeach Tetarly with evidence of bias pertaining to their divorce four years earlier. Defendant argued that Tetarly had attempted to hit him with her car, which was supported by a police report, and assaulted him while he was driving, which resulted in Tetarly’s arrest on domestic violence charges. The Court of Appeals denied defendant’s motion for an evidentiary hearing pursuant to People v Ginther, 390 Mich 436; 212 NW2d 922 (1973),1 and held that defense counsel was not ineffective for failing to impeach Tetarly because the record lacked evidence to show that she was still upset over the divorce. People v Trakhtenberg, unpublished opinion per curiam of the Court of Appeals, issued March 27, 2007 (Docket No. 268416). Defendant applied for leave to appeal in this Court, which was denied. People v Trakhtenberg, 480 Mich 856 (2007).
Defendant subsequently filed a legal malpractice claim against defense counsel, which the trial court dismissed upon defense counsel’s motion for summary disposition. The Court of Appeals affirmed, holding that defense counsel’s performance fell within the “attorney [45]*45judgment rule.” Trakhtenberg v McKelvy, unpublished opinion per curiam of the Court of Appeals, issued October 27,2009 (Docket No. 285247).2 See, also, Simko v Blake, 448 Mich 648; 532 NW2d 842 (1995). Meanwhile, in his criminal case, defendant filed a motion for relief from judgment under MCR 6.508(D)(3), claiming that he was entitled to a new trial because he was denied the effective assistance of trial and appellate counsel and, alternatively, that newly discovered evidence warranted a new trial. The trial court denied the motion under MCR 6.508(D)(3)(b), and the Court of Appeals denied defendant leave to appeal. People v Trakhtenberg, unpublished order of the Court of Appeals, entered March 20, 2009 (Docket No. 290336). In lieu of granting leave to appeal, this Court retained jurisdiction and remanded the case to the Court of Appeals for consideration as on leave granted, and the Court of Appeals was ordered to remand the case to the trial court to conduct a Ginther hearing in order to evaluate defendant’s claims. People v Trakhtenberg, 485 Mich 1132 (2010).
During the course of the Ginther hearing, voluminous testimony was taken. Tetarly admitted that she was dissatisfied with the divorce judgment and had made negative comments about defendant in front of the complainant. And, for the first time, Tetarly disclosed that before reporting the complainant’s allegations of abuse to the authorities, she brought the complainant to a youth pastor. Tetarly stated that she then brought the complainant to CARE House, which provides intervention and treatment services for child victims of abuse, where Amy Allen, a CARE House [46]*46employee, performed a forensic interview, during which the complainant alleged the abuse. The responding detective’s police report states that the detective asked Tetarly to directly ask the complainant whether defendant had ever touched her “private parts” with his fingers. That questioning eventually led to the complainant’s second formal allegation of abuse.
Allen, who was unaware that the complainant had spoken to others about the abuse, testified that it is important to know whether the child has spoken to anyone else in order to conduct a proper forensic interview because, as a result of repeated interviewing, a child might start to mistakenly believe that something happened to him or her. Additionally, Dr. Katherine Okla, a clinical psychologist specializing in sexual abuse, noted her concern regarding the complainant’s knowledge of her mother’s hatred of defendant and explained that Tetarly’s leading and suggestive questions and the repeated questioning of the complainant (especially in a therapeutic rather than forensic setting) could have tainted the child’s recollection of the events surrounding the alleged abuse. Defendant testified that he had requested that defense counsel consult with numerous witnesses including Allen and HT, who was defendant’s son.
Defense counsel testified that her defense theory was two-fold: she would (1) impeach the complainant’s trial testimony with an inconsistent statement regarding the number of times defendant made her touch him and (2) show that defendant lacked the requisite intent of sexual gratification to be convicted of CSC-II.3 Addition[47]*47ally, she advised defendant to waive his preliminary examination, and she did not demand discovery, obtain Allen’s notes, or interview any witnesses because she felt that any further information was irrelevant to the defense theories. Defense counsel testified that she was unaware of the complainant’s continued therapy, her feelings toward defendant, her testimony in the civil trial that defendant applied medication to her vagina, and her meeting with a youth pastor.
Following the hearing, the trial court ruled that defense counsel was ineffective and defendant was entitled to a new trial. The Court of Appeals reversed, reasoning, in part, that collateral estoppel precluded the Court from reviewing the performance of defense counsel because in defendant’s legal malpractice case, the Court had held that defense counsel’s performance fell within the “attorney judgment rule.” The Court further held that counsel was not ineffective on the basis of the claims of error left for its review. People v Trakhtenberg, unpublished opinion per curiam of the Court of Appeals, issued May 19, 2011 (Docket No. 290336). Defendant sought leave to appeal in this Court, which we granted. People v Trakhtenberg, 490 Mich 927 (2011).
II. STANDARD OF REVIEW
This Court reviews de novo the application of a legal doctrine, including collateral estoppel. Estes v Titus, 481 Mich 573, 578-579; 751 NW2d 493 (2008). The question whether defense counsel performed ineffectively is a mixed question of law and fact; this Court reviews for clear error the trial court’s findings of fact and reviews de novo questions of constitutional law. People v Armstrong, 490 Mich 281, 289; 806 NW2d 676 (2011).
[48]*48III. ANALYSIS
A. COLLATERAL ESTOPPEL
Generally, the proponent of the application of collateral estoppel must show “that (1) a question of fact essential to the judgment was actually litigated and determined by a valid and final judgment, (2) the same parties had a full and fair opportunity to litigate the issue, and (3) there was mutuality of estoppel.” Estes, 481 Mich at 585.4 When the application of collateral estoppel “crosses over” the line between a criminal and a civil proceeding, it has aptly been termed “cross-over estoppel.”5 Several Court of Appeals opinions have held that a criminal defense attorney may rely on the doctrine of collateral estoppel in order to avoid malpractice liability when a full and fair determination was made in a previous criminal action that the same client had received effective assistance of counsel. See, e.g., Barrow v Pritchard, 235 Mich App 478, 484-485; 597 NW2d 853 (1999). Yet we must hesitate to apply collateral estoppel in the reverse situation — when the government seeks to apply collateral estoppel to preclude a criminal defendant’s claim of ineffective assistance of counsel in light of a prior civil judgment that defense counsel did not commit malpractice.
The prosecution argues that this Court approved the application of collateral estoppel in the civil-to-criminal context in People v Gates, 434 Mich 146; 452 NW2d 627 (1990). Gates stated that “[c]ases involving ‘cross-over estoppel,’ where an issue adjudicated in a civil proceed[49]*49ing is claimed to be precluded in a subsequent criminal proceeding, or vice versa, are relatively recent and rare.” Id. at 155. And further, the United States Supreme Court has stated that “the doctrine of collateral estoppel is not made inapplicable by the fact that this is a criminal case, whereas the prior proceedings were civil in character.” Yates v United States, 354 US 298, 335; 77 S Ct 1064; 1 L Ed 2d 1356 (1957), overruled on other grounds by Burks v United States, 4371 US 1; 98 S Ct 2141; 57 L Ed 2d 1 (1978). It is unnecessary to discuss the relevant holdings of these cases, however, because the prosecution and the Court of Appeals have ignored a fundamental aspect of this case that distinguishes it from Gates and Yates. In this case, defendant is not the proponent of the application of collateral estoppel; to the contrary, the prosecution asked the Court to apply the doctrine to estop the Court’s full review of defendant’s claim that he received ineffective assistance of counsel.6
In the present case, we must consider the goal of the doctrine of collateral estoppel along with the elements of the doctrine to determine whether the Court of Appeals erred when it precluded review of many of defendant’s allegations concerning the ways in which defense counsel erred. The doctrine of collateral estop-pel has compelling underpinnings because it “relieve [s] [50]*50parties of the cost and vexation of multiple lawsuits, conservéis] judicial resources, and, by preventing inconsistent decisions, encourage[s] reliance on adjudication.” Allen v McCurry, 449 US 90, 94; 101 S Ct 411; 66 L Ed 2d 308 (1980), citing Montana v United States, 440 US 147, 153-154; 99 S Ct 970; 59 L Ed 2d 210 (1979). Further, collateral estoppel “also promote[s] the comity between state and federal courts that has been recognized as a bulwark of the federal system.” Allen, 449 US at 96, citing Younger v Harris, 401 US 37, 43-45; 91 S Ct 746; 27 L Ed 2d 669 (1971). That said, collateral estoppel “must be applied so as to strike a balance between the need to eliminate repetitious and needless litigation and the interest in affording litigants a full and fair adjudication of the issues involved in their claims.” Storey v Meijer, Inc, 431 Mich 368, 372; 429 NW2d 169 (1988) (emphasis added). In determining whether the party opposing collateral estoppel has had a “full and fair” opportunity to adjudicate his or her claim, a court must take into consideration the
choice of forum and incentive to litigate .... [A]s so often is the case, no one set of facts, no one collection of words or phrases, will provide an automatic formula for proper rulings on estoppel pleas. In the end, decision will necessarily rest on the trial courts’ sense of justice and equity. [Blonder-Tongue Laboratories, Inc v Univ of Illinois Foundation, 402 US 313, 333-334; 91 S Ct 1434; 28 L Ed 2d 788 (1971).]
See, also, Storey, 431 Mich at 373 (stating that “[t]he extent to which the doctrine is applied is also dependent upon the nature of the forum in which the initial determination was rendered”).
We hold that the Court of Appeals erred when it applied collateral estoppel to preclude its review of defendant’s ineffective-assistance-of-counsel claim be[51]*51cause defendant did not have a full and fair opportunity to litigate his claim in the malpractice proceeding. Considering the nature of the forum in which defendant’s allegations concerning counsel’s errors were initially rejected, it is clear that defendant’s interest when pursuing his civil malpractice claim differed from his interest in asserting his constitutional right to effective counsel in the criminal proceeding. Indeed, defendant sought monetary gain in the malpractice case, whereas in his criminal case he seeks protection of a constitutional right and his liberty. Accordingly, because defendant has a different and most likely stronger incentive to litigate counsel’s errors in the criminal proceeding, the prior civil litigation concerning counsel’s alleged claims of error did not afford defendant a full and fair opportunity to litigate his ineffective-assistance-of-counsel claim.
Because we conclude that the Court of Appeals erred when it applied collateral estoppel, which precluded a full review of defense counsel’s alleged errors, we must now decide the merits of defendant’s ineffective-assistance-of-counsel claim on the basis of a full review of the evidence revealed at the evidentiary hearing.
B. INEFFECTIVE ASSISTANCE OF COUNSEL
Both the Michigan and the United States Constitutions require that a criminal defendant enjoy the assistance of counsel for his or her defense. Const 1963, art 1, § 20; US Const, Am VI. In order to obtain a new trial, a defendant must show that (1) counsel’s performance fell below an objective standard of reasonableness and (2) but for counsel’s deficient performance, there is a reasonable probability that the outcome would have been different. Armstrong, 490 Mich at 290; see, also, People v Pickens, 446 Mich 298; 521 NW2d 797 (1994) [52]*52(adopting the federal constitutional standard for an ineffective-assistance-of-counsel claim as set forth in Strickland).
X. DEFENSE COUNSEL’S PERFORMANCE
In examining whether defense counsel’s performance fell below an objective standard of reasonableness, a defendant must overcome the strong presumption that counsel’s performance was born from a sound trial strategy. Strickland, 466 US at 689. Yet a court cannot insulate the review of counsel’s performance by calling it trial strategy. Initially, a court must determine whether the “strategic choices [were] made after less than complete investigation,” and any choice is “reasonable precisely to the extent that reasonable professional judgments support the limitations on investigation.” Id. at 690-691. Counsel always retains the “duty to make reasonable investigations or to make a reasonable decision that makes particular investigations unnecessary.” Id. In this case, the trial court and the Court of Appeals erred by failing to recognize that defense counsel’s error was the failure to exercise reasonable professional judgment when deciding not to conduct any investigation of the case in the first instance.7 Accordingly, no purported limitation on her investigation of the case can be justified as reasonable trial [53]*53strategy.8 We hold that because defense counsel failed to exercise reasonable professional judgment when deciding to forgo particular investigations relevant to the defense, her representation fell below an objective standard of reasonableness.
First, defense counsel failed to identify the factual predicate of each of the five charged counts of CSC-II. Although the charging documents lacked specific factual allegations, defense counsel advised defendant to waive his preliminary examination and she failed to file a motion for a bill of particulars. As a result, in this case defense counsel was left without a competent understanding of the prosecution’s theories of guilt. In fact, Jerome Sabbota, an expert in criminal trial practice and defending cases involving allegations of criminal sexual conduct, testified at defendant’s evidentiary hearing that without either a preliminary examination or a bill of particulars, there was no way to develop a defense in this case.
Second, defense counsel failed to consult with key witnesses who would have revealed weaknesses of the prosecution’s case. Particularly, counsel failed to interview Allen, despite the fact that the prosecution in-[54]*54eluded her on its witness list. Moreover, given the exposure the complainant had to multiple interviews and leading questions, a reasonable attorney would have consulted an expert, such as Okla, to testify regarding the propriety of how the complainant made her allegations. Yet the only expert defense counsel consulted was John Neumann, an expert in sex offender evaluation.9 Perhaps most importantly, defense counsel stated at the Ginther hearing that she chose not to consult any witnesses or obtain additional evidence before she decided to pursue a defense strategy for which she concluded that no further investigation was necessary.
Lastly, defense counsel’s unreasonably inadequate investigation contributed to her failure to sufficiently develop the defense that was actually presented at trial. This case turned solely on credibility — the ultimate question at trial was whether the complainant’s allegations of sexual abuse were truthful or, conversely, if her allegations were the result of improper motivations and interviewing techniques. Counsel’s failure to cross-examine Tetarly and adequately impeach the complainant was a result of counsel’s unreasonable decision to forgo any investigation in the case. In fact, counsel admitted that had she discovered the pertinent information, she would have (1) impeached the complainant with her additional inconsistent statements regarding the number of times defendant allegedly forced her to [55]*55touch him, (2) impeached the complainant and Tetarly regarding the complainant’s impression that defendant did not love her, and (3) consulted experts and Allen regarding proper forensic-interviewing protocol. Also, counsel failed to employ reasonable professional judgment when deciding not to interview HT, who was also listed on the prosecution’s witness list. HT was intimately familiar with the relationship between defendant and the complainant. Thus, an attorney exercising reasonable professional judgment would have at least spoken to HT in an attempt to determine if he could provide testimonial evidence that might have corroborated defendant’s testimony.
Therefore, we hold that defense counsel’s performance was constitutionally deficient because a sound defense strategy cannot follow an incomplete investigation of the case when the decision to forgo further investigation was not supported by reasonable professional judgment. We must now turn to the question whether defendant was prejudiced by the deficiency.10
2. PREJUDICE11
In addition to proving that defense counsel’s representation was constitutionally deficient, defendant [56]*56must show that “but for counsel’s deficient performance, a different result would have been reasonably probable.” Armstrong, 490 Mich at 290, citing Strickland, 466 US at 694-696. A defendant may meet this burden “even if the errors of counsel cannot be shown by a preponderance of the evidence to have determined the outcome.”12 Strickland, 466 US at 694. And “[w]here there is relatively little evidence to support a guilty verdict to begin with (e.g., the uncorroborated testimony of a single witness), the magnitude of errors necessary for a finding of prejudice will be less than where there is greater evidence of guilt.” Brown v Smith, 551 F3d 424, 434-435 (CA 6, 2008), citing Strickland, 466 US at 696.
In the present case, the key evidence that the prosecution asserted against defendant was the complainant’s testimony; therefore, the reliability of defendant’s convictions was undermined by defense counsel’s failure to introduce impeachment evidence and evidence that corroborated defendant’s testimony. The defense strategy not to present the trier of fact with vital evidence was the result of counsel’s failure to employ [57]*57reasonable professional judgment, which limited counsel’s knowledge of the existence and importance of that evidence.
Regarding the impeachment evidence, while it is true that defense counsel cross-examined the complainant, the omissions in that cross-examination, coupled with defense counsel’s failure to cross-examine Tetarly, deprived the trier of fact of the necessary and available evidence that discredited the complainant’s allegations. Similarly, in Armstrong, 490 Mich at 292, this Court held that, although the complainant was cross-examined by defense counsel, “a reasonable probability exists that this additional attack on the complainant’s credibility [the introduction of cell phone records] would have tipped the scales in favor of finding a reasonable doubt about defendant’s guilt.”13 Had counsel exercised reasonable judgment when investigating the case, she would have been able to impeach the complainant’s testimony with the complainant’s additional inconsistent statements and with expert testimony that discredited the propriety of the complainant’s accusations. Further, defense counsel’s failure to impeach Tetarly left the record completely devoid of any motivation that Tetarly may have had to distort and encourage the complainant’s allegations. Without this evidence, “in a case that essentially boil[s] down to whether the complainant’s allegations of [criminal sexual conduct] [are] true,” we have no doubt that the [58]*58reliability of defendant’s convictions is adequately called into question. Id. at 293.
Likewise, defense counsel’s failure to corroborate the defense that defendant did not have the intent of sexual gratification compounded the prejudicial effect of defense counsel’s failure to impeach the complainant’s testimony. She did not ask the complainant if defendant had previously applied ointment to her for medical purposes. If she had, presumably, the complainant would have answered in the affirmative, given that she testified accordingly in a later civil proceeding. Likewise, defense counsel did not consult with HT, who likely would have offered testimony that corroborated defendant’s testimony.14 Instead, counsel relied solely on defendant’s testimony that he did not possess the requisite intent.
Therefore, if defense counsel had exercised reasonable professional judgment, she would have discovered and presented impeachment evidence and evidence that corroborated defendant’s testimony, and there is a reasonable probability that the result of the trial would have been different. Thus, defendant has shown that he was unfairly prejudiced by defense counsel’s errors.
IV CONCLUSION
We conclude that collateral estoppel cannot be applied to preclude the review of a criminal defendant’s claim of ineffective assistance of counsel simply because a previous civil proceeding determined that defense counsel had not committed malpractice. Application of collateral estoppel on that basis fails to satisfy the element of the doctrine [59]*59requiring that a defendant previously have had an opportunity to fully and fairly litigate his or her ineffective-assistance-of-counsel claim.
Furthermore, defense counsel’s performance in this case was constitutionally inadequate and rendered defendant’s trial unfair and unreliable. Therefore, we reverse the judgment of the Court of Appeals and remand this case to the trial court for a new trial.
Marilyn Kelly, Markman, and Mary Beth Kelly, JJ., concurred with CAVANAGH, J.