Legal castrations in the US - just or inhuman?

In the  US state of Alabama, Representative Steve Hurst is trying to pass a new bill that is to make child molesters pay for their crime in a very sincere way. The bill he presents is to make it legal to castrate sex offenders if they are above the age of 21 and whose victims might be 12 or younger. 

This sentence is not a new penalty in the USA since already nine other states such as California, Florida, Georgia, Iowa Louisiana, Montana, Oregon, Texas and Wisconsin already has a kinda of simillar law that would enforce a chemical castration that causes a lack of interest for having sex. Steve's bill is set up for the 2014  legislative session, but the details of how the castration process goes are not included in this bill.

Now some see this bill as removing human rights and is simply just not the right thing to do. It also says under the eight amendment in the American Constitution: Prohibits excessive fines and excessive bail, as well as cruel and unusual punishment. Which means that the US government can't "cruel and unsual punishments" such as castration. Amnesty International has referred to this law as "inhuman treatment". Either if the castration is carried out either chemically or surgically, the outcome will still be the same.

So now I want to ask you good people out there about what you actually think about this law.

Is this law inhumane or are sex offenders deserving of such a punishment?