I really doubt that many women drug incapacitated men with Viagra in order to rape sperm out of them. These are the actions of an incredibly disturbed individual and I'm sure not a common occurrence. In that case it is very unfortunate for the man that he is involved with a mentally ill person and the appropriate actions need to be worked out amongst the individuals involved.

If a woman lies to a man about being on birth control, that is also wrong, but unfortunately human beings lie to each other and make bad decisions. If a man has an extramarital affair and lies about it and gets another woman pregnant the wife doesn't get to tell the mistress to keep or not even though it affects her future as well. The man lied and produced an unwanted child, but the other woman should still choose what happens to her and her child ultimately.

Men need to protect themselves if they truly want to make sure they don't reproduce when they don't want to. The culture of placing the blame on the woman for unwanted children is bad for women and men both. Birth control has a failure rate even when used properly, and many women don't use it properly. Men need to grow up and acknowledge that the more sex you have, the higher statistical chance you have to create a child. No matter what your partner is saying doing, you have to realize that if you want to have sex, you may end up with consequences. If you want to make absolute sure you won't be held responsible for a child, stop having sex.

I know that men will continue to have sex, so what can they do to protect themselves?

Maybe only engaging in sex with people you know well enough to be able to be certain of their integrity, respect and honesty is a first step. Take an active interest in birth control, go with your GF to the doctor and talk about the birth control options you have as a couple, talk openly about how you feel about children and your plans for the future. Maybe considering a vasectomy while freezing sperm for a future plan for children could work for men who are more well off. If being "trapped" into caring for a child you didn't plan for is such a threat to men, you'd think they'd take more actions before a pregnancy occurs to protect themselves from this situation.

It is common that women, who are sexual creatures just like men, should be responsible for saying no, for always controlling their desires, for not getting pregnant and ultimately held 100% responsible for and event that involved two adults. Men understand where babies come from, they just feel like they should be able to indiscriminately put their sperm wherever they want and them when the inevitable happens they don't want to be held accountable for their actions.

In conclusion, human relationships are complicated and there are lots of factors that lead to unplanned pregnancy. Men choose to have sex and they know that sex can lead to pregnancy. Having good communication and trust in your sexual partners can go a long ways, but even when everything is being done "right" pregnancy can still happen. Even if a woman says she'd have an abortion if she did get pregnant, that doesn't mean she will follow through. Sex is a risk, don't do it unless you are ready to take the consequences.

If men start caring more about their role in family planning and being more involved and open in the process they can protect themselves from dishonest strangers they probably shouldn't be having sex with anyways.

But if you really got raped by some chick with Viagra, then I feel for you. Some people are just crazy, but we shouldn't build laws around extreme examples of irresponsibility,