“[T]he suppression by the prosecution of evidence favorable to an accused ... violates due process where the evidence is material either to guilt or to punishment, irrespective of the good faith or bad faith of the prosecution.” Banks v. Dretke, 540 U.S. 668, 691, 124 S.Ct. 1256, 157 L.Ed.2d 1166 (2004) (quoting Brady, 373 U.S. at 87, 83 S.Ct. 1194). “When the ‘reliability of a given witness may well be determinative of guilt or innocence,’ nondisclosure of evidence affecting credibility falls within this general rule.” Giglio v. United States, 405 U.S. 150, 154, 92 S.Ct. 763, 31 L.Ed.2d 104 (1972) (quoting Napue v. Illinois, 360 U.S. 264, 269, 79 S.Ct. 1173, 3 L.Ed.2d 1217 (1959)).

To prevail on a Brady claim, “[t]he evidence at issue must be favorable to the accused, either because it is exculpatory, or because it is impeaching; that evidence must have been suppressed by the State, either willfully or inadvertently; and prejudice must have ensued.” Strickler, 527 U.S. at 281-82, 119 S.Ct. 1936.

Evidence is material where there exists a “reasonable probability” that had it been disclosed the result at trial would have been different. Banks, 540 U.S. at 699, 124 S.Ct. 1256. “A ‘reasonable probability’ is a probability sufficient to undermine confidence in the outcome.” United States v. Bagley, 473 U.S. 667, 682, 105 S.Ct. 3375, 87 L.Ed.2d 481 (1985).

Under AEDPA, we do not decide de novo whether a state prisoner has sufficiently proven a Brady violation. See Yarborough v. Alvarado, 541 U.S. 652, 665, 124 S.Ct. 2140, 158 L.Ed.2d 938 (2004) (“We cannot grant relief under AEDPA by conducting our own independent inquiry into whether the state court was correct as a de novo matter.”); Neal v. Puckett, 286 F.3d 230, 236 (5th Cir.2002) ( en banc ) (“We have no authority to grant habeas corpus relief simply because we conclude, in our independent judgment, that a state supreme court's application of [federal law] is erroneous or incorrect.”). Rather, we decide whether the state court's Brady determination resulted in a decision that is contrary to, or involved an unreasonable application of, clearly established federal *478 law. Busby v. Dretke, 359 F.3d 708, 717 (5th Cir.2004).FN4

FN4. “The statute compels federal courts to review for reasonableness the state court's ultimate decision, not every jot of its reasoning.” Santellan v. Cockrell, 271 F.3d 190, 193 (5th Cir.2001); see Neal, 286 F.3d at 246 (holding that a federal court's “focus on the ‘unreasonable application’ test under section 2254(d) should be on the ultimate legal conclusion that the state court reached and not on whether the state court considered and discussed every angle of evidence”).

Here, the TCCA accepted every factual finding and conclusion of law of the state habeas court except the conclusion that “harm” may be “presumed” from the result in the case. In citing Strickler and Kyles, the TCCA rejected the state trial court's conclusion that any impeachment evidence in the withheld pretrial interviews was material. We review this dispositive determination through the deferential lens provided by Congress in AEDPA. See Rompilla v. Beard, 545 U.S. 374, 125 S.Ct. 2456, 2462, 162 L.Ed.2d 360 (2005) (stating that, under AEDPA, the state court decision must have been not only incorrect or erroneous but objectively unreasonable).

Dickson argues that Brown's pretrial interview was material to the issue of intent because “[o]ne can only speculate on the outcome of the trial if the corroboration testimony of Mr. Medina was challenged at trial with the undisclosed tape of Mr. Brown. Both Mr. Brown and Mr. Medina may have been impeached since one story corroborated another.” But alleging a speculative outcome is insufficient.

Rather, a petitioner must demonstrate a reasonable probability that the result at trial would have been different. Banks, 540 U.S. at 698-99, 124 S.Ct. 1256. Petitioner has not done so. See United States v. Moore, 452 F.3d 382, 388 (5th Cir.2006) (“[V]ague assertions do not establish any exculpatory evidence, let alone a reasonable probability that such evidence affected the outcome of the trial.”).

His argument regarding Dane Dickson's pretrial interview statement is similarly deficient. Although suggesting that he could have used the statement, Petitioner does not establish how the result at trial would have been different. Id.

Even if we assume the defense could have effectively impeached Brown and Dane Dickson, other probative evidence of an intent to kill prevents us from concluding that the state court determination of immateriality resulted in a decision that involves an unreasonable application of federal law. The State offered evidence that Petitioner: (1) carried a loaded gun into the store; (2) admitted to firing the gun that killed Carmelo Surace; and (3) killed Marie Surace shortly thereafter.

Furthermore, the prosecution presented evidence that Petitioner intended to rob the store by force or threat of force, including: (1) testimony that, in the weeks before the offense, Petitioner stated a desire to rob a store; (2) evidence that Petitioner stole three .22 caliber rifles prior to the robbery; and (3) evidence that Petitioner sawed off the barrel of the rifle and whittled the stock so that it could be concealed.

The state court could reasonably conclude that this combined evidence rendered the undisclosed impeachment evidence immaterial because confidence in the outcome was not undermined. See Kopycinski v. Scott, 64 F.3d 223, 226 (5th Cir.1995) (examining corroborating evidence and stating that the materiality inquiry assesses whether disclosure “would have placed the case in a different light so as to undermine confidence in the jury verdict”); Edmond v. Collins, 8 F.3d 290, 294 (5th Cir.1993) (noting that nondisclosed impeachment evidence is cumulative and immaterial*479 when the witness was impeached sufficiently at trial).FN5

FN5. Although a competent defense attorney might have used the taint of bias and misrecollection as to Brown to diminish the effectiveness of Medina's testimony, we cannot say that the TCCA unreasonably concluded that the evidence was immaterial given the other evidence of intent presented at trial. See United States v. Weintraub, 871 F.2d 1257, 1262 (5th Cir.1989) (“Courts have found ... that impeachment evidence improperly withheld was not material where the testimony of the witness who might have been impeached was strongly corroborated by additional evidence supporting a guilty verdict. In contrast, where the withheld evidence would seriously undermine the testimony of a key witness on an essential issue or there is no strong corroboration, the withheld evidence has been found to be material.”) (citations omitted).

We affirm the district court's denial of relief because, even assuming the pretrial interview recordings contained beneficial impeachment evidence, other evidence of Petitioner's intent to kill prevents this court from concluding that the state court's immateriality determination resulted in a decision that involved an unreasonable application of federal law. See Yarborough, 541 U.S. at 665, 124 S.Ct. 2140 (“Although the question of what an ‘unreasonable application’ of law might be difficult in some cases, it is not difficult here.”).

We pause, however, to express our concern regarding the State's failure to turn over pretrial interview statements by two key witnesses in a death penalty case. The duty of a prosecutor, as the representative of the sovereign in a criminal case, is “not that it shall win a case, but that justice shall be done.” Berger v. United States, 295 U.S. 78, 88, 55 S.Ct. 629, 79 L.Ed. 1314 (1935); see United States v. Leon, 468 U.S. 897, 900-01, 104 S.Ct. 3405, 82 L.Ed.2d 677 (1984) (recognizing the goal of establishing “procedures under which criminal defendants are ‘acquitted or convicted on the basis of all the evidence which exposes the truth’ ” (quoting Alderman v. United States, 394 U.S. 165, 175, 89 S.Ct. 961, 22 L.Ed.2d 176 (1969))). “Unless, indeed, the adversary system of prosecution is to descend to a gladiatorial level unmitigated by any prosecutorial obligation for the sake of truth, the government simply cannot avoid responsibility for knowing when” disclosure is required. Kyles, 514 U.S. at 439, 115 S.Ct. 1555.

Accordingly, a prosecutor faithfully discharges his duty where he fully understands his obligations under Brady, not where, as here, he fails to “consciously th[ink] about it one way or the other.”

At oral argument, the State conceded the tapes contain impeachment evidence and implied that an attorney with a “better understanding” of Brady would have disclosed them.FN6 Although the trial prosecutor apparently believed these recordings were protected work product, these recorded pretrial interview statements contain no protected attorney opinion.FN7 Even *480 if the prosecutor wrongly believed the statements contained some protected attorney opinion, he should have known that the duty lay with the trial judge, not the prosecutor, to weigh the need for confidentiality against the defendant's need to use the material to obtain a fair trial.FN8

FN6. Concession of a disclosure obligation under Brady does not, of course, concede a redressable Brady violation. See Strickler, 527 U.S. at 281, 119 S.Ct. 1936 (noting that “the term ‘ Brady violation’ is sometimes used to refer to any breach of the broad obligation to disclose exculpatory evidence ... although, strictly speaking, there is never a real ‘ Brady violation’ unless the nondisclosure was so serious that there is a reasonable probability that the suppressed evidence would have produced a different verdict”).

FN7. The Supreme Court has not decided “whether Brady requires a prosecutor to turn over his work product.” Mincey v. Head, 206 F.3d 1106, 1133 n. 63 (11th Cir.2000). At least one commentator states: “Because Brady is based on the Constitution, it overrides court-made rules of procedure. Thus, the work-product immunity for discovery in Rule 16(a)(2) prohibits discovery under Rule 16 but it does not alter the prosecutor's duty to disclose material that is within Brady.” 2 Charles Alan Wright, Federal Practice and Procedure § 254.2 (3d ed.2000).

Although some jurisdictions recognize that “opinion work product” may enjoy some protection, see, e.g., Williamson v. Moore, 221 F.3d 1177, 1182 (11th Cir.2000), the State agreed at oral argument that the prosecutor's assertion of work product in this case was “obviously wrong.”

FN8. See In re: United States, 397 F.3d 274, 285 (5th Cir.2005) ( “In the ordinary case, a party must claim privilege with specificity, and a court can ultimately demand in camera review of privileged documents.”); Thomas v. State, 837 S.W.2d 106, 114 (Tex.Crim.App.1992) ( en banc) (asserting that an in camera inspection by the trial court accommodates the interest of the State in protecting the identity of informants and the interest of the defendant in Brady evidence); see also United States v. Phillips, 854 F.2d 273, 277 (7th Cir.1988) (“[W]hen a criminal defendant seeks to discover information contained in confidential government files, the trial court must balance the competing interests of the defendant and the government in deciding whether and in what form such discovery will be allowed.”); United States v. Dupuy, 760 F.2d 1492, 1501 (9th Cir.1985) (“Consultation with the judge is particularly appropriate when the Government has legitimate reasons for protecting the confidentiality of the material requested, for the trial judge can then weigh the Government's need for confidentiality against the defendant's need to use the material in order to obtain a fair trial.”); United States v. Bocra, 623 F.2d 281, 285 (3d Cir.1980) (“The submission of discovery materials to the court for an in camera inspection and decision as to which materials are discoverable is commonly used when the Government's need for preserving confidentiality over the materials must be balanced with the defendant's constitutional right to evidence material to his defense.”).

“Courts, litigants, and juries properly anticipate that ‘obligations [to refrain from improper methods to secure a conviction] ... plainly rest[ing] upon the prosecuting attorney, will be faithfully observed.’ ” Banks, 540 U.S. at 696, 124 S.Ct. 1256 (citation omitted) (alteration in original). Indeed, the preservation of our civil liberties depends upon the faithful and ethical exercise of power by those who bear the mantle of public trust. See Cheney v. U.S. Dist. Court for D.C., 542 U.S. 367, 386, 124 S.Ct. 2576, 159 L.Ed.2d 459 (2004) (“The rigors of the penal system are ... mitigated by the responsible exercise of prosecutorial discretion” by a “publicly accountable prosecutor ... under an ethical obligation, not only to win and zealously to advocate for his client but also to serve the cause of justice.”).

Where, as here, the actions of officials are contrary to these aspirational principles, whether for improper or guileless reason, courtroom victories may prove pyrrhic, and such conduct “should attract no judicial approbation.” Banks, 540 U.S. at 696, 124 S.Ct. 1256.FN9

FN9. See Brady, 373 U.S. at 87, 83 S.Ct. 1194 (“Society wins not only when the guilty are convicted but when criminal trials are fair; our system of the administration of justice suffers when any accused is treated unfairly.”); id. at 87-88, 83 S.Ct. 1194 (“A prosecution that withholds evidence ... which, if made available, would tend to exculpate [a defendant] or reduce the penalty helps shape a trial ... that does not comport with standards of justice, even though ... his action is not ‘the result of guile[ ]’....”).

We AFFIRM the district court's denial of relief under 28 U.S.C. § 2254.