State v. Myers (Conn. 2025): Clarifying When the Exclusion of Third-Party Culpability Evidence is Merely Evidentiary, Not Constitutional

Introduction

State v. Myers, officially released on 12 August 2025 by the Supreme Court of Connecticut, addresses two perennial issues in criminal trials: (1) the admissibility of third-party culpability evidence, and (2) the permissible boundaries of prosecutorial questioning that insinuates a defence obligation to produce forensic testing. While the underlying facts concern the brutal 2018 stabbing of the defendant’s ex-girlfriend, the precedential value of the decision lies in the Court’s doctrinal statements on harmless-error review and burden-shifting. The Court unanimously affirmed the conviction, but in doing so drew a sharper distinction between evidentiary error and constitutional violation where third-party culpability evidence is excluded.

Summary of the Judgment

• Third-party Culpability Evidence: The trial court excluded several pieces of evidence pertaining to the victim’s neighbour, Mark Adduci (e.g., a bizarre video, a voicemail to his girlfriend, prior misconduct and post-crime mental-health deterioration). Assuming arguendo that the exclusions were erroneous, the Supreme Court ruled that:
  • The error was not of constitutional dimension because the defence did present substantial evidence pointing to Adduci, and the excluded items were tangential rather than central.
  • Accordingly, the non-constitutional harmless-error standard applied; the defendant bore the burden to prove the jury was “substantially swayed.”
  • Given the strength of the State’s forensic, documentary and testimonial proof, the defendant could not make that showing.
• Mistrial / Burden-Shifting Claim: On redirect, the prosecutor elicited from a detective that defence counsel had never asked for certain towels to be DNA tested. The defence moved for a mistrial, claiming unconstitutional burden-shifting. The trial court issued prompt curative instructions and denied the motion. The Supreme Court upheld that ruling, finding no abuse of discretion; the instructions adequately dispelled any inference that the defence had a duty to produce evidence.
• Result: Judgment of conviction for murder affirmed; the defendant’s 57-year sentence stands.

Analysis

(A) Precedents Cited and Their Influence

1. State v. Jordan, 329 Conn. 272 (2018).
   Jordan introduced the principle that exclusion of evidence is not constitutional error if the defendant still meaningfully presents the defence. Myers relies heavily on Jordan’s footnote 14 to place the harmless-error burden on the defendant.
2. State v. Hedge, 297 Conn. 621 (2010). Hedge defines the threshold “direct connection” standard for third-party culpability evidence. The trial court used Hedge to admit some and exclude other items; the Supreme Court assumed arguendo that Hedge was misapplied but held any error harmless.
3. State v. West, 274 Conn. 605 (2005) and State v. Cerreta, 260 Conn. 251 (2002). Both cases compare probative value of third-party physical evidence. The Court analogised Adduci’s mere presence in a stairwell (as argued by the defence) to the weak fingerprints in West, rather than the highly incriminating DNA in Cerreta.
4. State v. Sinclair, 332 Conn. 204 (2019); State v. Osimanti, 299 Conn. 1 (2010). Both articulate the two-tier harmless-error analysis—constitutional vs. non-constitutional—that Myers crystallises.
5. Harmless-error lineage (State v. Fernando V., 331 Conn. 201 (2019); State v. Massaro, 347 Conn. 200 (2023)) is used to show the Court’s “fair assurance” that guilt was not impacted.
6. Burden-shifting & mistrial cases: State v. Holley, 327 Conn. 576 (2018); State v. Ortiz, 280 Conn. 686 (2006); State v. Cook, 262 Conn. 825 (2003). These provided the deferential abuse-of-discretion framework for denial of a mistrial.

(B) Court’s Legal Reasoning

1. Centrality Test. The majority measured whether each excluded item was “central” to the defence. Because the jury heard:
   • Adduci’s presence near the screams;
   • His angry texts to the victim;
   • Evidence he misled police and initially avoided contact; and
   • Police consideration of him as a suspect (including DNA swab),
   the Court deemed the barred evidence cumulative or peripheral.
   
   
2. Harmless-Error Allocation. Having labelled the error non-constitutional, the Court placed the burden on the defence to show “substantial sway.” They reviewed:
   • Physical evidence (victim’s blood on defendant, defendant’s DNA under victim’s fingernails);
   • Voluminous harassing contacts and incriminating notes;
   • Inconsistent statements by the defendant;
   • Lack of any forensic link to Adduci.
   The Court concluded the State’s case was overwhelming and the defence theory speculative.
3. Burden-Shifting Allegation. The Court found that the prosecutor’s two questions about defence opportunities to test evidence:
   • Did not explicitly assert a defence obligation;
   • Were neutralised by immediate and final jury instructions emphasising the State’s burden and the permissibility of negative inferences from police failure to test evidence.
   Hence, no “severe” prejudice necessitating mistrial.

(C) Anticipated Impact on Future Litigation

• Recalibrated Strategic Calculus. Defence counsel should note that Myers raises the bar for re-branding evidentiary rulings as constitutional error. Unless exclusion guts the entire defence, appellate courts will treat the issue as non-constitutional; appellants must show actual prejudice.
• Trial Court Gatekeeping. Trial judges gain implicit confirmation that they can exclude marginal third-party evidence without automatically implicating the Sixth Amendment, so long as sufficient avenues remain to present the theory.
• Prosecutorial Questioning. The decision tolerates limited references to a defence’s ability to test evidence, so long as the jury is clearly reminded that no such duty exists. Prosecutors, however, are warned that explicit or repeated insinuations may still trigger reversals.
• Appellate Framework. Myers synthesises harmless-error factors (probative value, cumulative nature, strength of State’s case) into a structured checklist likely to be cited in future opinions.

Complex Concepts Simplified

Third-Party Culpability Evidence

Evidence suggesting someone other than the defendant committed the crime. Connecticut follows the “direct connection” test: the evidence must link the third party to the specific offence, not merely show bad character.

Constitutional vs. Evidentiary Error

A ruling is “constitutional” error if it infringes rights under the U.S. or state constitution (e.g., confrontation, right to present a defence). Otherwise, it is “evidentiary.” The classification dictates who bears the burden on appeal: the State (constitutional) or the defendant (evidentiary).

Harmless-Error Analysis

An appellate technique asking whether the verdict “was substantially swayed” by the error. Factors: importance of the evidence, whether it was cumulative, corroboration/contradiction elsewhere, scope of cross-examination, overall strength of prosecution.

Burden-Shifting

An improper suggestion that the defendant must prove innocence or produce evidence. The prosecution must bear the full, unshifted responsibility to prove guilt beyond a reasonable doubt.

Mistrial

A drastic remedy that terminates the trial mid-course due to prejudicial events that cannot be cured by instructions or other measures.

Conclusion

State v. Myers does not revolutionise third-party culpability jurisprudence, but it crystallises a critical doctrinal boundary: the exclusion of non-central, cumulative third-party evidence is an evidentiary misstep, not a constitutional one, and therefore shifts the appellate burden to the defendant. Simultaneously, the judgment reinforces the discretion trial courts have in denying mistrials when prompt, clear instructions can correct any misimpression regarding the burden of proof. Defence counsel must now marshal a stronger showing that excluded evidence was indispensable if they hope to invoke constitutional harmless-error review. Prosecutors and judges, in turn, can rely on Myers as a roadmap for evaluating, curing and, when necessary, defending evidentiary rulings on appeal.