In R v Bree [2007] EWCA 256, the Court of Appeal explored the issue of capacity and consent, stating that, if, through drink, or for any other reason, a complainant had temporarily lost her capacity to choose whether to have sexual intercourse, she was not consenting, and subject to the defendant's state of mind, if intercourse took place, that would be rape. However, where a complainant had voluntarily consumed substantial quantities of alcohol, but nevertheless remained capable of choosing whether to have intercourse, and agreed to do so, that would not be rape. Further, they identified that capacity to consent may evaporate well before a complainant becomes unconscious. Whether this is so or not, however, depends on the facts of the case.
In cases similar to Bree, prosecutors should carefully consider whether the complainant has the capacity to consent, and ensure that the instructed advocate presents the Crown's case on this basis and, if necessary, reminds the trial judge of the need to assist the jury with the meaning of capacity.
Prosecutors and investigators should consider whether supporting evidence is available to demonstrate that the complainant was so intoxicated that he/she had lost their capacity to consent. For example, evidence from friends, taxi drivers and forensic physicians describing the complainant's intoxicated state may support the prosecution case. In addition, it may be possible to obtain expert evidence in respect of the effects of alcohol/drugs and the effects if they are taken together. Consideration should be given to obtaining an expert's back calculation or the opinion of an expert in human pharmacology in relation to the complainant's level of alcohol/ drugs at the time of the incident.