Self enforcement of rape law: Markets in everything.

A doctor has invented a female condom with teeth.

Ehlers is distributing the female condoms in the various South African cities where the World Cup soccer games are taking place.

The woman inserts the latex condom like a tampon. Jagged rows of teeth-like hooks line its inside and attach on a man's penis during penetration, Ehlers said.

Once it lodges, only a doctor can remove it -- a procedure Ehlers hopes will be done with authorities on standby to make an arrest.

"It hurts, he cannot pee and walk when it's on," she said. "If he tries to remove it, it will clasp even tighter... however, it doesn't break the skin, and there's no danger of fluid exposure."

How does it deter? How do signal you are wearing one? Since it seems unlike you can signal you are wearing one, do enough females have to use the product for it to have a deterrent effect? What about the free rider problem?

With some adaptation this seems more like a variation on a chastity belt to me.