Although expert witnesses may testify about the general behavioral characteristics of sexual abuse victims, they cross the line into impermissible vouching and ultimate issue testimony when they opine that a particular complainant has exhibited those general behavioral characteristics. Following a jury trial, Anthony Favoccia, Jr., was convicted of two counts of risk of injury to a child and found not guilty of second degree sexual assault, in connection with the alleged sexual assault of a friend's daughter. The Appellate Court reversed the conviction. The state appealed claiming that the Appellate Court improperly concluded that the trial court abused its discretion in admitting into evidence statements by an expert witness that the complainant exhibited behaviors consistent with those of sexual abuse victims and that the improper rulings were not harmless. The majority of the Supreme Court panel affirmed the Appellate Court's judgment, agreeing that the challenged statements were improperly admitted and that reversal was required. Connecticut cases since the 1989 Connecticut Supreme Court case of State v. Spigarolo, have recognized the value of generalized expert testimony to explain to the jury what might seem to be atypical behavior exhibited by victims of assaults, so long as that opinion testimony does not directly vouch for their credibility or veracity. Subsequent case law has emphasized the danger of an expert, particularly one who has treated or evaluated a complainant, vouching indirectly for that complainant's credibility as well. This case fell between the generalized behavioral testimony admissible under Spigarolo and the more pointed diagnoses held inadmissible, such as in the 2005 case of State v. Iban C. The majority limited expert testimony about the behavioral characteristics of child sexual assault victims admitted under Spigarolo to that which is stated in general or hypothetical terms and precluded opinion testimony about whether the specific complainant exhibited such behaviors. The majority found that the trial court abused its discretion in permitting the challenged testimony and did not have a fair assurance that the improper evidence did not substantially sway the verdict, given such factors as the state's case not being particularly strong, the jury reporting a deadlock and returning a split verdict. Justice Palmer dissented, agreeing that the linking testimony should be barred but disagreeing that it was harmful here. Justice Zarella dissented, disagreeing that such testimony should be precluded.

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