Statutory Insanity Defenses Unaffected by Voluntary Induction of Mental State

Introduction

State v. Wierson, decided May 28, 2025 by the Supreme Court of Georgia, clarifies the scope of Georgia’s two statutory insanity defenses—mental incapacity (OCGA § 16-3-2) and delusional compulsion (OCGA § 16-3-3)—and overrules a 1982 decision, Bailey v. State, that had imposed a judge-made exception when a defendant “voluntarily” induced her own mental state. Michelle Wierson, charged with vehicular homicide and reckless driving after a fatal crash, sought to plead not guilty by reason of insanity. The State sought to bar that defense by introducing evidence that Wierson had ceased her psychiatric medications weeks before the collision. The questions presented were:

Whether voluntary medication non-compliance is relevant to the availability of Georgia’s statutory insanity defenses;
Whether Bailey v. State, 249 Ga. 535 (1982), should be reaffirmed or overruled.

Summary of the Judgment

The Supreme Court affirmed the Court of Appeals:

Statutory text and context make clear that a defendant’s mental capacity at the time of the offense is the sole inquiry under OCGA §§ 16-3-2 and 16-3-3, regardless of how that mental state arose.
Bailey’s rule—that one who “brought about” a delusion voluntarily cannot invoke Georgia’s insanity defenses—was a judicially invented exception unsupported by statutory language or legislative intent and is overruled.
Evidence that Wierson stopped taking medication weeks before the crash is irrelevant to whether she may invoke the insanity-defense statutes and thus was properly excluded on relevance grounds.

Analysis

1. Precedents Cited

Bailey v. State (1982): Held, without meaningful statutory analysis, that a defendant who intentionally induces a psychotic state cannot invoke the insanity defenses—a rule later deemed judge-made and overruled in Wierson.
Code Ann. 1933 § 26-303 (and predecessors back to 1817): Recognized a defendant as culpable only for acts committed during “lucid intervals,” focusing exclusively on mental capacity “at the time” of the offense.
OCGA § 16-3-4 (Intoxication defense): By expressly barring voluntary intoxication, demonstrates the legislature knows how to carve exceptions—yet enacted no parallel exception in the insanity statutes.
Wilson v. State (1911), Murphy v. State (1943), Orange v. State (1948): Georgia cases holding that evidence of behavior before and after an offense may help prove mental state at the time of the crime, but do not treat self-inducement as a bar.

2. Legal Reasoning

The Court applied established canons of statutory interpretation:

Plain Meaning: OCGA §§ 16-3-2 and 16-3-3 turn solely on the defendant’s mental capacity or compulsion “at the time of” the criminal act or omission.
Context and Structure: The adjacent intoxication statute contains an explicit voluntary-intoxication exception (OCGA § 16-3-4(c)), signaling that the General Assembly knew how to create such carve-outs and chose not to do so for insanity defenses.
Expressio Unius: Where the legislature expressly included one exception but omitted another in statutes addressing like subjects, the omission is deliberate.
Stare Decisis: Bailey’s holding arose from a cursory, unreasoned transplant of the intoxication exception into the insanity statutes. It disregarded the text, structure, and legislative history of Georgia law and therefore undermines the rule of law. The Court overruled it accordingly.

3. Impact

State v. Wierson has three principal effects on Georgia criminal practice:

Clarity in Insanity Pleas: Defendants remain entitled to plead not guilty by reason of insanity whenever they meet the statutory criteria, without fear that evidence of prior medication non-compliance will bar the defense as a matter of law.
Limits on Prosecution’s Evidence: Prosecution may not introduce medication non-compliance merely to argue that the defendant “voluntarily” caused her own insanity defense to fail. Such evidence remains admissible only to show whether the defendant in fact lacked capacity or suffered delusional compulsion “at the time of” the offense.
Legislative Prerogative: If the legislature deems it appropriate to deny the statutory insanity defenses to defendants who cease prescribed medication, it must amend the statutes explicitly rather than rely on judge-made exceptions.

Complex Concepts Simplified

“Mental Incapacity” Defense (OCGA § 16-3-2): Excuses criminal liability if, during the crime, a defendant could not tell right from wrong due to mental illness or defect.
“Delusional Compulsion” Defense (OCGA § 16-3-3): Excuses liability when, at the time of the crime, a mental delusion overmastered the defendant’s will to resist committing the offense.
Expressio Unius Est Exclusio Alterius: A rule of statutory construction meaning “the expression of one thing implies the exclusion of others.”
Stare Decisis: The principle that courts should follow prior decisions to ensure legal stability, disturbed only when a precedent is unreasoned or fundamentally wrong.

Conclusion

State v. Wierson reaffirms that Georgia’s statutory insanity defenses turn exclusively on a defendant’s mental state “at the time” of the offense, not on how that state arose. In overruling Bailey v. State, the Court restores fidelity to the text and structure of OCGA §§ 16-3-2 and 16-3-3 and entrusts to the legislature any policy decision to carve out exceptions. The decision brings welcome clarity to insanity defense practice, preserves the separation of legislative and judicial roles, and ensures that defendants are judged only by the criteria the General Assembly prescribed.