People v. Santarelli

Joseph Santarelli (defendant) killed his brother-in-law. At trial, Santarelli asserted an insanity defense and produced lay and expert testimony to support this claim. To rebut this defense, the prosecution (plaintiff) introduced expert testimony that Santarelli suffered from a personality disorder known as explosive personality. According to the expert testimony, explosive personality could result in behavioral outbursts but did not rise to the level of delusional psychosis, which would qualify for the insanity defense. To further this line of argument, the prosecution introduced testimony of laypeople who had witnessed Santarelli react to situations in violent, irrational ways. Specifically, a witness testified that Santarelli had been in a bar fight, although the witness was unable to say how the fight started. Another witness testified that Santarelli had beaten up a teamster shop steward as part of a preplanned attack. Finally, Santarelli’s probation officer testified that Santarelli had previously been convicted of possession of a sawed-off shotgun and that he had on several occasions reacted violently in the face of mild provocation. Santarelli was convicted, and he appealed, arguing that the prosecution’s lay testimony about his prior violent acts was improperly admitted. The appellate court affirmed. Santarelli appealed.