In February 2000, George Demarais and Matthew Trombley (defendant) were involved in a bar fight. Shortly after the altercation, the men left the bar. According to Demarais, Trombley then grabbed Demarais from behind and punched him numerous times, compelling Demarais to brandish a small knife in self-defense. Trombley testified that he acted in self-defense and that in an effort to stop Demarais from stabbing him, Trombley repeatedly punched Demarais after feeling the sharp pains of Demarais’s knife. Both men were injured during the struggle. The State of Vermont (plaintiff) charged Trombley with aggravated assault under 13 V.S.A. § 1024(a)(1) for “purposely caus[ing] bodily injury to another.” The trial judge instructed the jury that Trombley could be found guilty of the offense if he either acted (1) purposely, with the conscious purpose of causing Demarais serious bodily harm, or (2) knowingly, understanding that he acted under circumstances in which it was practically certain that his conduct would cause Demarais serious bodily injury. The trial judge also provided instructions on the justification of self-defense. The jury convicted Trombley of aggravated assault. Trombley appealed, contending that the trial judge erred by permitting the jury to consider whether Trombley acted knowingly, because the statute under which Trombley was charged required purposeful action.