I've just checked the legislation itself, and the basis for this prosecution isn't even outlined in the legislation itself, it seems to be based on case law based on judgement of what constitutes 'having the capacity to make that choice'
The original legislation specifies that it would be rape if the person were asleep, unconscious, had been given drugs / alcohol without their consent that incapacitated them etc but nothing at all about the person having voluntarily got themselves drunk and therefore being incapable of giving their consent.
So despite the legislation clearly defining 6 situations in which the person wouldn't be deemed as being capable of giving their consent, the courts seem to have come up with their own additional reason that wasn't in the original legislation based on their judgemet of what constitutes 'having the capacity to make that choice'.
http://www.legislation.gov.uk/ukpga/2003/42/pdfs/ukpga_20030042_en.pdf
http://www.legislation.gov.uk/ukpga/2003/42/pdfs/ukpga_20030042_en.pdf
http://www.legislation.gov.uk/ukpga/2003/42/pdfs/ukpga_20030042_en.pdf
which is presumably why lots of people seem to have assumed she must have been passed out, as that would have been the situation within the original legislation in which this would have classed as rape, not being a bit pissed but essentially with it.
As far as I can tell, the judge in this case based his guidance to the jury on the CPS guidance, which itself references the case
R v Bree 2007, which went to the court of appeal, where the appeal court judges actually declined to define specifically what should constitute someone being too drunk to consent, instead giving broad guidance similar to that given by the judge in this case, and the CPS. The odd thing being that in that case the person involved was acquitted.
So I think I may well be right that this case here actually is the first case to set the precedent with a conviction based on that appeal court judgement, or one of the first.
The judge said that the key test was whether the alleged victim had through drink or other substances lost her capacity to consent. If, through drink a woman had lost her capacity to consent, sexual intercourse would be rape. Conversely, an alleged victim who had drunk “substantial quantities” could still consent to sex. The capacity to consent, said the judge, could evaporate before sexual intercourse took place.
So if you lot would actually call off the dogs for a minute you might actually consider that this isn't exactly a standard cut and dried rape case, it's either the first of its kind to be found guilty on this basis, or one of the first, and it's based on appeal court judgements of what the word 'capacity' should mean rather than anything that was actually debated and agreed in parliament on the subject.
Surely if parliament had intended for this to be the situation then they would have added in a 7th paragraph to section 75 (2) which specified that a person who was under the incapacitated through drink or drugs they'd taken themselves voluntarily would also be considered to be incapable of consenting.
Instead parliament left it as being someone who was actually passed out, or had been spiked, but a few appeal court judges determined that this wasn't sufficient and added in an extra classification themselves.