Reaffirming Prejudice Requirement in §2254 Ineffective Assistance Claims: Caballero v. Miller

Introduction

Caballero v. Miller is a Second Circuit summary order, decided April 2, 2025, which addresses the interplay between the Strickland standard for ineffective assistance of counsel and the deferential review mandated by the Antiterrorism and Effective Death Penalty Act of 1996 (AEDPA), 28 U.S.C. § 2254(d). Petitioner‐Appellee Andrew Caballero was convicted of second‐degree murder in 2014 for the 1995 stabbing and rooftop push that killed Jason Kollman. Caballero’s trial and direct appeal counsel did not pursue certain investigative leads suggesting an alternative suspect, Michael Lugo. On collateral habeas review, the district court granted relief, concluding trial counsel’s investigation failures were objectively unreasonable and prejudicial. The State appealed. The Second Circuit reversed, holding that (1) under AEDPA deference, Caballero failed to show the state court unreasonably applied Strickland, because he did not identify what exculpatory evidence a fuller investigation would have produced; and (2) appellate counsel was not deficient for failing to raise issues requiring evidence outside the trial record.

Summary of the Judgment

The Second Circuit reversed the district court’s grant of habeas relief under 28 U.S.C. § 2254.
It held that Caballero failed to establish “prejudice” under Strickland v. Washington, 466 U.S. 668 (1984), because he did not proffer what additional testimony or evidence a more thorough investigation would have revealed.
The court emphasized the double deference owed to state‐court decisions: Strickland’s highly deferential performance and prejudice standards and AEDPA’s requirement that the state court’s ruling not be an unreasonable application of clearly established federal law.
It further held that appellate counsel was not constitutionally deficient for failing to raise the ineffective‐assistance claim on direct appeal, because New York law required that such claims, grounded in evidence outside the trial record, be brought in collateral proceedings.

Analysis

Precedents Cited

Strickland v. Washington (466 U.S. 668, 1984): Established the two‐pronged test for ineffective assistance—deficient performance and prejudice.
28 U.S.C. § 2254(d) (AEDPA): Limits federal habeas relief to state decisions that are contrary to or involve an unreasonable application of clearly established federal law.
Harrington v. Richter (562 U.S. 86, 2011): Emphasized the doubly deferential standard when Strickland and AEDPA apply together.
Knowles v. Mirzayance (556 U.S. 111, 2009): Clarified that the standard is whether the state court’s decision was objectively unreasonable, not merely incorrect.
Pinholster (563 U.S. 170, 2011): Reinforced the need for a “substantial” likelihood of a different outcome, not just a conceivable one.
Lindstadt v. Keane (239 F.3d 191, 2d Cir. 2001): Demonstrated a situation where the failure to investigate indeed prejudiced the petitioner by depriving him of key exculpatory testimony.
Schulz v. Marshal (345 F. App’x 627, 2d Cir. 2009): Showed that where an uninvestigated witness later identifies another perpetrator, prejudice is clear.
Pierotti v. Walsh (834 F.3d 171, 2d Cir. 2016): Applied New York law requiring collateral proceedings for claims based on evidence outside the trial record.
Lynch v. Dolce (789 F.3d 303, 2d Cir. 2015): Established the application of Strickland’s prejudice prong in the appellate‐counsel context.

Legal Reasoning

1. Strickland/AEDPA Deference
The court emphasized that a state court’s rejection of an ineffective assistance claim must stand unless it is an “unreasonable application” of Strickland. Here, the New York trial‐court and appellate‐court findings that Caballero failed to show prejudice were not unreasonable. Although trial counsel did not interview all Rosario witnesses or investigate Michael Lugo as an alternative suspect, Caballero presented no evidence—witness affidavits or offer of proof—describing what tangible benefit a fuller investigation would have yielded.

2. Prejudice Requirement
Under Strickland, a petitioner must show a “reasonable probability” of a different outcome absent counsel’s errors. Caballero pointed to the lack of physical evidence and inconsistencies in the testimony of the State’s key witnesses (Balarezo and Sierra), but those points were already exploited at trial by counsel’s cross‐examination. No testimony or affidavits demonstrated that the unseen witnesses would have provided admissible, exculpatory or impeaching evidence beyond what defense counsel already elicited.

3. Appellate Counsel Performance
New York procedural law requires most ineffective‐assistance claims to proceed in section 440.10 collateral motions rather than direct appeal when they rely on evidence outside the trial record. Caballero’s appellate counsel reasonably declined to raise a claim that could not be fully developed on the face of the trial record. Even absent that procedural rule, there was no prejudice because Caballero cannot show that appellate counsel would have prevailed in demonstrating a reasonable probability of a different outcome.

Impact

Caballero v. Miller reinforces the principle that under AEDPA and Strickland, petitioners challenging the adequacy of counsel’s investigation must identify the specific exculpatory or impeaching evidence that would have emerged. It underscores:

The critical importance of the Strickland “prejudice” prong in habeas proceedings—general assertions of deficient performance will not suffice in the absence of a proffer of actual, beneficial evidence.
The double-layer of deference federal courts owe state-court decisions on ineffective assistance under § 2254(d).
New York’s procedural rule that counsel on direct appeal need not—and should not—raise claims requiring development of facts outside the record, which belong in collateral proceedings.

Future habeas petitions in the Second Circuit asserting investigation failures will struggle unless they demonstrate with affidavits or offers of proof what unique, admissible material documents or witness testimony would have been obtained and how it would have changed the verdict.

Complex Concepts Simplified

AEDPA Deference (28 U.S.C. § 2254(d)): Federal courts may grant habeas relief only if the state court decision was contrary to or an unreasonable application of clearly established federal law.
Strickland Test: Two‐step inquiry: (1) Was counsel’s performance objectively unreasonable? (2) Was there a reasonable probability the result would have been different?
Rosario Material: Prior statements of prosecution witnesses that must be disclosed to the defense under People v. Rosario (N.Y. 1961).
Summary Order: A non‐precedential ruling by an appellate panel on routine matters; still binding on the parties.
Collateral vs. Direct Appeal: Direct appeals review the trial record; collateral motions (e.g., CPL 440.10 in New York) allow expansion beyond the record to develop new evidence.

Conclusion

Caballero v. Miller reaffirms that a habeas petitioner bears the burden of proving both deficient performance and actual prejudice under Strickland, and that under AEDPA, a state court’s reasonable application of those principles is entitled to deference. Bare complaints of inadequate investigation do not suffice—petitioners must identify the precise evidence or testimony they lost. The decision also clarifies that appellate counsel is not ineffective for omitting claims that cannot be resolved on the trial record and belong instead in collateral proceedings. This ruling fortifies the rigorous standards protecting both fair representation and finality of convictions in federal habeas review.