In theory, law is supposed to be a reflection of the people's will, developed over time. That's not always the case, but it's supposed to be what society commonly believes is fair set of rules.
Once upon a time, a King or Queen would dictate the law and it was held that a King or Queen themselves were 'above the law'. That was eventually abolished to the point where we created the phrase 'nobody is above the law' - not even the Monarchy.
Now we have specific laws for rape, and they are actually quite simple laws in principle, but they are notoriously hard to prosecute.
They are hard to prosecute not because the law specifically favours the male, but because we have a fundamental tenet of innocence until proven guilty, which places a burden of proof on the accuser not the accused. We then have a second issue in that most cases have no independent witnesses, and are often occurring in a situations where both parties are known to each other for a period of time prior (even if a matter of hours) and where the giving of consent isn't always a highly formalised process. Even when consent is given, it may be withdrawn at any time. Furthermore, there is still scope for a mismatch of beliefs where one party believes consent has been given and the other believes it has not, or has been withdrawn.
I will give one typical example (that most of us can envisage) where the issue of consent can be so complex...
A couple meet and agree to have sex, perhaps with their inhibitions diminished by alcohol, but both retaining the capacity to consent.
The couple engage in sex freely.
The following morning, in a sleepy stupor, the male elects to penetrate the female and does so for a small period of time.
The female awakes and no longer shares the desire to have sex with the male, the male accepts her decision, but the female objects to the fact he has already penetrated her and alleges rape.
The male maintains he had reasonable belief that consent was given.
The female believes she only consented to sex the previous night, but not the following morning.
It does not necessarily hold that if a female believes she was raped that she actually was, nor does it hold that if a man is found not guilty that the woman is a liar.
Equally the man may not have intended any harm whatsoever, but may be guilty of rape.
Even if the onus on consent was for the male to prove consent was given, it would not help us much. We still have a situation where a man may say 'she said yes, I asked her, repeated, and she agreed it was ok' and the female says 'That's a lie'. It is so very difficult to ascertain which is telling the truth when the agreement was formed or declined behind closed doors.
Notwithstanding all of that, we know statistically that few women make false allegations. It does happen, but it's relatively rare. However, it is very difficult in criminal law to make a judgment based on statistical likelihood, and even if it were possible, we would then end up with a self-fulling set of statistics where more convictions would further skew the statistics against the male.
The determination of consent is also complex - and this is partly why we end up looking at behaviour prior to the alleged rape.
The defendant who is pleading not guilty will invariably claim consent was given, which will give rise to the question 'How did you ascertain consent?'. He is likely to either say 'I asked and she said yes', or 'we kissed, touched, she agreed to come to my room and allowed me to continue...'
This is going to lead to the court examing the truth of this claim by seeing CCTV of the events leading up to the alleged rape.What choice does the court have in trying to establish how believable the story is?
This is a real paradox - because the law is clear, a woman can engage in whatever sexual behaviour she likes and can say no at ANY time and the man must stop. This is absolutely unambiguous.
However, a defendant is also trying to prove consent was given and usually has no proof of this (as people do not sign a contract). The only available evidence is a general feel for how he came to believe that sex was consenting hence examination of behaviour prior.
I believe THIS last paradox is the biggest problem in rape cases and it's one that there is no simple solution for.
I would like to see previous behaviour ruled out of evidence (but not events leading up to the act), but even this can be quite problematic.