In Canada, for example, it is illegal to kiss your sleeping wife, because (a) a kiss is a sexual act, (b) there is no de minimis exception to sexual assault, and (c) even if your wife explicitly consented in advance to being kissed while asleep, that consent ended when she fell asleep (in spite of that being the precise circumstance to which she wished to consent). (R v JA)
As another example, a man who lies about using birth control is committing a sexual assault, while a woman who lies about using birth control is not; the supreme court took the view that the possibility of becoming a mother is harmful, while the possibility of becoming a father is not. (R. v. Hutchinson)
As far as I'm aware, no other legal jurisdiction has followed Canada's example in either of these contexts.
it is illegal to kiss your sleeping wife
a man who lies about using birth control
It may be worth noting here that child support is considered to be something to which the child is entitled, regardless of to whom the money is in fact paid; there have been cases where rapists have received court-ordered child support payments from their victims.
Women have been known to take sperm from a used condom and impregnate themselves. If that happened to you, you would still be liable for child support.
What exactly is the point of such a law?
We're not talking lawsuits here. We're talking about criminal law, where there is no requirement for the alleged victim to feel aggrieved or even to consent to the prosecution.
If you kiss your sleeping wife, then mention this fact in passing to a police officer, you could theoretically find yourself being arrested and thrown in jail, since you confessed to a serious crime.
Very few countries have such laws. In most Western countries sexual intercourse without objection between two adults that are capable of consenting/objecting (no abuse of authority, no threat, no force) will not be regarded as rape.
This would be a very extreme definition of rape, because when you think about it, who would actually commit the rape if both persons did not object? Did both persons rape each other?
Legally, yes. The same applies if both persons are too intoxicated to be able to consent; and in some states without "romeo and juliet" laws, if two underage persons have sex.
Of course, it's up to prosecutors in such circumstances to decide whether to prosecute none, one, or both parties...
Modern public opinion != legal opinion. It varies wildly between jurisdictions. And what's on the law books isn't necessarily what's effectively enforced. In some jurisdictions, there is no effective way to prosecute for rape within marriage.
Whereas where I am, it's apparently legally required to continually get positive verbal consent throughout the act (as told to me by a legal student ~2 years ago), though this hasn't been tested in courts, and seems to be written to a fantasy of how humans behave; it doesn't matter how enthusiastic you are about getting consent, if you're not verbalising it constantly, then technically a crime is going on. Tough for you if you are turned off by talking during the act. Of course, take this to court and you're faced with the usual he-said/she-said problem of rape cases.
Legal definitions of rape - the definitions that count - vary considerably.