Reporter’s Note

The statute, 13 V.S.A. § 4801, places the burden of proof on the defendant.  The Supreme Court upheld the constitutionality of the statute in State v. Messier, 145 Vt. 622 (1985).  The statute does not relieve the State’s burden of proving all of the essential elements – including any mental element, beyond a reasonable doubt.

In 2024, the Committee revised the insanity instruction to better track the statutory language, as reflected in Judge Pacht’s jury instructions in State v. Aita Gurung, 3261-9-19 Cncr. The revised instruction now uses the language “lacked adequate capacity.”

For discussion on the interaction between diminished capacity and insanity, see State v. Webster, 2017 VT 98, ¶ 20, 206 Vt. 178 (“Diminished capacity and insanity are related concepts pertaining to defendant’s state of mind at the time of the offense”; however, while defendant must prove affirmative defense of insanity, diminished capacity “is an attempt to defeat the State’s obligation to show the necessary intent to commit the crime”); State v. Bourgoin, 2021 VT 15, ¶¶ 25­–27 (trial court did not err by not instructing jury on its own motion that State’s expert’s sanity opinion was irrelevant to defendant’s claimed diminished capacity, where “State never claimed . . . that [expert’s] ultimate opinion on defendant’s sanity was relevant to whether defendant had the requisite intent to commit second-degree murder” and where “both defendant . . . and the trial court . . . emphasized the distinction between determining whether defendant was insane and determining whether he had the requisite intent to commit second-degree murder”).