Experts should not express opinions about whether sexual activity was by consent without sufficient foundation: Tuhura v R  NZCA 246 (10 June 2010).
The accused had been convicted of vaginal and anal sexual violation. His defence was consent. Of central importance was his claim that the complainant had invited him to return to her residence later that night. There was contested medical evidence, to the effect that injuries to the complainant were unlikely to be the result of consensual intercourse.
The Court of Appeal took the opportunity to review cases where expert opinion of this nature had been regarded as being without foundation, and concluded that this was such a case. The Court asked that its judgment be distributed to prosecutors, defence counsel and relevant doctors.
The kinds of injuries that have been held not to support an opinion that they were unlikely to be the result of consensual intercourse are (and here you may want a map):
- Three fresh lacerations in the area of the fossa navicularis
- Lacerations in the region of the anus, no injuries to the hymen or posterior forchette
- Tenderness and abrasions in the vaginal area, thickish brown discharge with pieces of traumatised tissue, some bruising
- Split in vaginal area of triangular shape in surface skin, 1 cm base and 2 cm on sides, quite red
- Three minor tears in vaginal area, longest 5 mm at mouth of vagina, tender areas at vaginal entrance and deep in vagina
- Superficial graze about 5 mm long on hymen
"56. ... In cases where the injuries suffered by the complainant are not such that a doctor can properly express a view as to whether the sexual contact prior to the injuries being incurred was consensual or not, the doctor should not be asked to express a view. If the question is asked, the response should indicate that he or she cannot properly express a view one way or the other. The issue of consent will be at the forefront of the jury's mind. There is a real risk that if an expert suggests that injuries are indicative of non-consensual sexual activity, jurors may decide the case on the false understanding that the fact that the complainant suffered injuries makes it more likely that the associated sexual contact was non-consensual."
The Court added (60) that in cases of more serious injury an opinion as to consent might be warranted.
Admission of the opinion evidence of non-consent here was a miscarriage of justice. This required the Court to consider the proviso, in particular to apply Matenga v R  NZSC 18 (commented on here, 20 July 2009, and see also 1 January 2010).
There is a small error in the judgment in the present case, Tuhura:
"89. We are satisfied that, apart from the admission of the contested medical evidence, the trial was fair. ..."
This seems to say, the trial was not fair because of the admission of the contested medical evidence.
Contrast that with the point made in Matenga, footnote 20:
"In R v Condon  1 NZLR 300 (SC) at paras  and  this Court equated breach of the right to a fair trial with a substantial miscarriage of justice."
That means the proviso cannot apply where the trial is unfair. In Matenga the Supreme Court continued (31), in a passage included in a quotation from that case in Turuha at 67:
"Before applying the proviso the Court must also be satisfied that the trial was fair [footnote: The assessment of fairness is to be made in relation to the trial overall: Condon at para ] and thus that there was no breach of the right guaranteed to the accused by s 25(a) of the Bill of Rights."
Plainly, the Court in Tuhura meant, in para 89, to say "notwithstanding" instead of "apart from", so that the passage quoted should have read:
"89. We are satisfied that, notwithstanding the admission of the contested medical evidence, the trial was fair. ..."
I emphasise this point because to some readers this case might open the door for submissions that a conviction at an unfair trial can be upheld on appeal. Matenga does not address in detail the relationship between a substantial miscarriage of justice and a fair trial, other than to say that an unfair trial is a substantial miscarriage of justice. It seems that, once an appellate court decides that a conviction was inevitable, being properly based on admissible evidence, the trial could only be called unfair if there had been a reasonable apprehension of bias, or if there had been an inequality of arms disadvantaging the defence, or if fresh evidence raised a reasonable doubt as to the safety of the conviction in the mind of the appellate court. My view is that "trial fairness" deserves its own heading in judgments in this area, because it addresses these distinct concerns.
The Tuhura Court concluded that there was no support in the evidence for the accused's contention that the complainant had invited him to her residence, and that in the absence of such an invitation the defence of consent could not raise a reasonable doubt. The appeal was dismissed.
Update: The Supreme Court refused leave to appeal: Tuhura v R  NZSC 128 (2 November 2010).