Proponents of castration argue that it is justified and appropriate, that by controlling sex offenders' irresistable urges to rape or molest again, castration allows them to be released without endangering the public. Of more than 700 Danish sex offenders castrated following multiple convictions, relapse rates dropped from between 17% and 50% to just 2%. A Norwegian study showed the same for selected male and female sex offenders (the women had their ovaries removed). In smaller studies in Scandinavia and Italy, chemical castration was equally effective in some groups of volunteer prisoners, with the most dramatic reductions among pedophiles.

These studies suggest the common argument-that rape is all about power, not sex, and therefore castration won't work-is wrong. A German study found that up to half of castrated men still could have erections and sex, but their desire was weakened or even extinguished. Johns Hopkins University psychiatrist and expert on treating sex offenders, Fred Berlin, points out that castration works "mainly in those who are sexually aroused by their crime...sadists and pedophiles."

Opponents of castration for repeat sex offenders cite the side effects of the drugs used in chemical castration as one reason castration should be avoided. Depo-Provera, the most widely used drug in the United States for castration, has very few side effects in the women it is prescribed to as a method of birth control. In men, not surprisingly, given that it is a female sex hormone, it has more. Some are trivial, but others can be dangerous for some men. It is inadvisable for men with high blood pressure to receive a weekly injection of the drug. Other side effects include serious allergic reactions and the formation of blood clots that can kill patients.