I think these are a terrible idea. (1) It's easy enough to insert a foreign object into a woman's vagina to check if she's wearing one of these, said condom hooks onto the foreign object, and the rapist's penis remains intact. More importantly, (2) if a rapist attempts to rape a woman and gets one of these nasty things cutting up his penis, what are the chances that he's going to fly into a rage? Fairly high, I'd say, and he's going to take that anger out on the woman. Maybe he'll just beat the crap out of her, or maybe he'll kill her.  In short, I can see how this would actually lead to increased violence against women, and I said the same thing when something similar came about years ago. :/  The only real way to stop rape, all rape, on a mass scale, is to change the messaging surrounding rape. As long as women are second class citizens, or worse, rape will always be present.