(concurring). I concur on the ground that the impeachment evidence at issue is not material under Brady v Maryland (373 US 83 [1963]). In light of that conclusion, there is no need to reach the question of whether the evidence was suppressed. However, since the majority resolves both of these prongs in the People’s favor, I write separately to express my belief that Detective O’Leary’s knowledge of the allegations pending against him in the federal lawsuit should be imputed to the People.
The majority’s determination that the evidence was not suppressed relies on the so-called “unrelated criminal activity exception” to the imputation doctrine, which provides that a police officer’s secret knowledge of his own misconduct in an unrelated case is not imputable to the People (Campiti v Matesanz, 186 F Supp 2d 29, 49 [D Mass 2002], affd 333 F3d 317 [1st Cir 2003], cert denied 540 US 931 [2003]; see also e.g. People v Kinney, 107 AD3d 563, 564 [1st Dept 2013]; People v Seeber, 94 AD3d 1335, 1336-1338 [3d Dept 2012]; People v Ortega, 40 AD3d 394, 395 [1st Dept 2007]; People v Roberson, 276 AD2d 446, 446 [1st Dept 2000]; People v Johnson, 226 AD2d 828, 828-829 [3d Dept 1996]; People v Vasquez, 214 AD2d 93 [1st Dept 1995]). The majority’s interpretation of suppression under Brady is patently contrary to the Supreme Court’s holding in Kyles v Whitley (514 US 419 [1995]) and subverts Brady’s fundamental concern with “insurfing] that the accused receives a fair trial” (People v Bryce, 88 NY2d 124, 129 [1996]; Strickler v Greene, 527 US 263, 280-281 [1999]). At its core, the majority’s suppression analysis relies on the problematic distinction “between the nondisclosure of police misconduct ‘which has some bearing on the case against the defendant,’ and the nondisclosure of such material which has ‘no relationship to the case against the defendant, except insofar as it would be used for impeachment purposes’ ” (majority op at 889, quoting Vasquez, 214 AD2d at 100). According to the majority, “when a police officer engages in illegal conduct in the course of his or her investigation or prosecution of the defendant, knowledge of that misconduct may be imputed to the People for Brady purposes, regardless of the officer’s motivation or the prosecutor’s actual awareness” (majority op at 888-889). On the other hand, when the misconduct is “collateral” to defendant’s case, the majority declares that the officer’s private knowledge thereof is not subject to imputation (see majority op at 889).
This distinction is arbitrary and illogical in the context of Brady’s suppression prong. Ultimately, the majority’s error lies *894in conflating imputation and materiality. The tangential nature of impeachment evidence has no bearing on whether a police officer’s knowledge thereof is attributable to the People. By contrast, the degree to which an officer’s bad acts may be characterized as collateral to a particular case is certainly relevant to determining whether the evidence is material, that is, whether the failure to disclose it “undermines confidence in the outcome of the trial” (Kyles, 514 US at 434, quoting United States v Bagley, 473 US 667, 678 [1985]).
In support of its suppression analysis, the majority invokes agency principles underlying the imputation doctrine, reasoning that a police officer is not acting as an “arm of the prosecution” when he conceals his own wrongdoing in an unrelated case (see majority op at 887-888, 889). It is difficult to square this conclusory position with the majority’s concession that an officer is considered a member of the prosecution team when he conceals ultra vires acts committed during the investigation or prosecution of the defendant (see majority op at 888-889). In both instances, it is the act of concealing evidence that constitutes the Brady violation. And in both instances, it is not the officer’s “status” as a member of law enforcement, but his role in the investigation and prosecution of defendant’s case that brings the concealment within the ambit of Brady (cf. United States v Stewart, 433 F3d 273, 298-299 [2d Cir 2006] [expert witness for the prosecution was not an “arm of the prosecution” when he provided false testimony because he “acted only in the capacity of an expert witness” and was not “in any way involved with the investigation or presentation of the case to the grand jury” or development of prosecutorial strategy]).
In other words, the majority’s appeal to agency principles
“misses the point of Brady. Perhaps the officer was not a state actor when he engaged in the underlying corrupt conduct, but he was a state actor when he testified against the defendant and concealed his misconduct from the defense. There can be no doubt that the officer knew that the evidence, which bears on his credibility, is favorable to the defense. If the evidence satisfies the standard of materiality, then his failure to disclose it violates Brady” (Robert Hochman, Brady v Maryland and the Search for Truth in Criminal Trials, 63 U Chi L Rev 1673, 1704 [1996]).
The majority’s position ignores the police officer’s independent obligation to disclose impeachment evidence and improperly *895conveys to the police the discretion to make the judgment call on what misconduct qualifies as “collateral.” This result presents precisely the sort of danger Kyles sought to avoid, namely, the unconstitutional substitution of “the police for the prosecutor, and even for the courts themselves, as the final arbiters of the government’s obligation to ensure fair trials” (Kyles, 514 US at 438).
Notably, while Kyles concerned suppressed evidence that related directly to the defendant’s case, the Supreme Court said nothing to imply that the scope of imputable knowledge should be so limited. Rather, the Court simply held that Brady material includes information “known only to police investigators and not to the prosecution]” (Kyles, 514 US at 438). Therefore, “the individual prosecutor has a duty to learn of any favorable evidence known to the others acting on the government’s behalf in the case, including the police” (id. at 437). Contrary to the majority’s position on the prosecutor’s “duty to learn,” courts addressing prior bad acts of police witnesses have interpreted Kyles more broadly.
For example, in Arnold v McNeil (622 F Supp 2d 1294 [MD Fla 2009], affd on op below 595 F3d 1324 [11th Cir 2010]), the District Court granted a petition for a writ of habeas corpus after determining that the collateral, illegal acts of the lead detective in a drug prosecution, which were unknown to the trial prosecutor, constituted Brady material. Citing Kyles, the court held that the detective’s “knowledge of his own criminal conduct, constituting evidence that would be favorable to the defense, demonstrate [d] that the prosecution both ‘possessed’ favorable evidence . . . and ‘suppressed’ exculpatory or impeachment evidence” (id. at 1316). That the detective’s misconduct in Arnold did not occur in the course of investigating the petitioner’s case, or participating in its prosecution, was not dispositive of the suppression issue. Instead, the collateral nature of the detective’s corrupt behavior affected the court’s assessment of whether the evidence was material. Ultimately, the court concluded that
“the illegal activities of [the detective] (many of which were strikingly close to the drug offense for which [the petitioner] was prosecuted), which were occurring at the precise time he was identifying [the petitioner] as the perpetrator and then testifying against him at trial, and [the detective’s] failure to *896disclose those activities to the prosecution so the prosecutor could disclose them to the defense, create[d] a reasonable probability that the outcome would have been different” (622 F Supp 2d at 1321 [internal quotation marks omitted]).
Moreover, the detective “was clearly a key member of the prosecution team whose information and testimony was vital to secure the conviction” (id. at 1315). On these facts, not only was the detective’s private knowledge of his own unrelated, unlawful acts imputed to the People, but it was also material under Brady, and the court granted the petitioner habeas relief (id. at 1322).
Similarly, the federal court in Campiti v Matesanz (186 F Supp 2d at 49) suggested that restricting imputation to police knowledge of misconduct committed in the instant case is untenable after Kyles. Indeed, after noting that a number of courts had “absolved the prosecution of responsibility for failing to disclose the unknown, unrelated criminal activity of its corrupt officers” (Campiti, 186 F Supp 2d at 49, citing United States v Rosner, 516 F2d 269 [2d Cir 1975]; Commonwealth v Waters, 410 Mass 224, 229, 571 NE2d 399, 402 [1991]; People v Vasquez, 214 AD2d 93 [1st Dept 1995]; People v Johnson, 226 AD2d 828 [3d Dept 1996]), the Campiti court expressed doubt as to whether those cases remained good law (see Campiti, 186 F Supp 2d at 49 [“Since Kyles established the applicable rule, the Commonwealth is hard-pressed to argue that it lacked responsibility for [the officer’s] failure to disclose his unlawful activity. The cases with similar factual circumstances cited by the Commonwealth were decided before Kyles, with the exception of Johnson, which did not cite or distinguish Kyles”]). Ultimately, the Brady claim in Campiti was rejected based on lack of materiality alone, and the court declined to reach the “knotty issue” of imputation (id.).
Applying Kyles in the manner proposed herein is also consistent with this Court’s precedent regarding imputation in similar contexts. For instance, in People v Wright (86 NY2d 591 [1995]) the defendant argued that the prosecution’s failure to turn over evidence that a prosecution witness had a “history as a police informant” constituted a Brady violation, warranting post-conviction relief (id. at 598). This Court agreed. We determined that the evidence “was both favorable and material to the defense” (id.). In addition, the fact that the witness’ previous status was known only to police did not excuse the *897prosecutor’s failure to disclose it (id., citing Kyles, 514 US at 437). Of particular relevance here is that the witness in Wright was not acting as an informant in that case (see 86 NY2d at 593-594). Therefore, the undisclosed information, like the federal civil rights allegations against O’Leary, constituted impeachment evidence arising from a prior case. But in Wright, we found that the People constructively possessed the information. Furthermore, we analyzed the value of the impeachment evidence, i.e., its relevance to the outcome at trial, under the materiality prong of Brady, concluding that under the circumstances, the collateral evidence was sufficiently material to warrant vacatur of the conviction (id. at 596-597; see also Seeber, 94 AD3d at 1338 [granting a motion to vacate pursuant to CPL 440.10 (1) (b) based on the misrepresentations of a State Police forensic scientist both in prior cases and the one sub judice; noting that “requiring a defendant to demonstrate that the People were aware of the subject misrepresentation in order to prevail . . . potentially sets the stage for a situation where a truly innocent person, whose conviction was obtained solely upon the basis of admittedly falsified, manufactured or otherwise unreliable evidence, might remain in prison simply because the People were unaware ... of misfeasance on the part of a law enforcement representative”]).
In sum, the exception endorsed by the majority imposes limits on the imputation doctrine that are wholly inconsistent with Kyles. That decision stands for the proposition that favorable, material evidence known only to police officers involved in a criminal investigation is not exempt from Brady’s disclosure requirements. Members of the prosecution team, including the police investigators such as Detective O’Leary here, are subject to the same disclosure obligations; the knowledge of every member of the team is imputed to the prosecution. There is no rational basis for charging the People with a police officer’s knowledge of his own misconduct in the defendant’s case but not with wrongdoings perpetrated by the same officer in another context. Consideration of the collateral nature of an officer’s prior bad acts is more properly undertaken at the materiality stage of the Brady analysis.
Frequently, the improper conduct will be tangential, or its impeachment value will be minimal in light of the strength of the other evidence of guilt, weighing in favor of a finding that its suppression was immaterial. Moreover, as here, lack of materiality will often obviate the need to reach the suppression *898prong (see e.g. Campiti, 186 F Supp 2d at 49-50). But, in the event that both favorability and materiality tip in defendant’s favor, the fact that the bad acts were perpetrated against a different suspect should not foreclose an otherwise meritorious Brady claim. The majority’s flawed imputation analysis undermines the due process protections which the Brady doctrine enshrines.
In light of the above, it is unnecessary to address issues concerning the extent of the People’s obligation to investigate the prior alleged misdeeds of police officers assigned to a particular case. Here, the detective’s knowledge of the allegations lodged against him by a suspect in a different case was sufficient to trigger the disclosure obligation. Therefore, defendant satisfied the suppression prong of the Brady test.
Smith, J.(concurring). We held in People v LaFontaine (92 NY2d 470 [1998]) and reaffirmed in People v Concepcion (17 NY3d 192 [2011]) that neither the Appellate Division nor our Court may consider, in a criminal appeal, issues that “were either decided in [the appellant’s] favor or not ruled on” by the court of first instance (LaFontaine, 92 NY2d at 474). Here, County Court denied defendant’s motion under CPL 440.10 solely on the ground that the prosecution had neither actual nor constructive knowledge of the allegations made in the federal complaint against Detective O’Leary. It did not consider the question of whether those allegations were “material” information — i.e. whether there was a reasonable probability that they would have changed the result of the case (People v Fuentes, 12 NY3d 259, 263 [2009]). The Appellate Division, however, did consider the materiality issue, and found the information material. One might think that this was obvious LaFontaine error, and that LaFontaine likewise bars this Court from deciding materiality.
But the majority holds that there is a distinction, for LaFontaine purposes, between “separate alternative grounds for decision” and mere prongs of a “single multipronged legal ruling” (majority op at 895 n 2). This distinction (not mentioned, as far as I know, in any previous discussion of LaFontaine) puzzles me. How is an appellate court to decide what is a separate alternative ground for decision and what is a prong? Why were not the alternative grounds for decision in LaFontaine — the existence of, and the necessity for, a valid and applicable warrant for the defendant’s arrest — prongs of a ruling on the arrest’s *899validity? Why were not the two issues in Concepcion — the existence of consent to the search and the applicability of the inevitable discovery doctrine — prongs of a ruling on whether the Fourth Amendment required suppression of the evidence?
I do not know. But I am not complaining. As I explained in my dissent in Concepcion, the LaFontaine rule itself makes little sense to me, and if followed consistently (which it has not been) it will work enormous mischief. I thus welcome the majority’s limitation of the rule — a limitation which perhaps amounts to an effective overruling of LaFontaine.
Judges Graffeo, Read and Pigott concur with Judge AbdusSalaam; Chief Judge Lippman concurs in result in an opinion in which Judges Smith and Rivera concur; Judge Smith in a separate concurring opinion in which Judge Pigott concurs.Order reversed and order of County Court, Suffolk County, reinstated.