Mandated contraception in the poor...?

Because I was having a bit of a difficult time finding something particularly interesting to post and discuss, I consulted my wife, who thought about something she had discussed in her Ethics class. The idea their class was tossing around is the right for poor people to bear children. The sole classmate of my wife who supported it referred to how children are born into the welfare system as a result of their parents being also on welfare. Also, there was an idea thrust forward that was describing the overpopulation of the United States and how that is a problem that would be mitigated by mandating temporary infertility. (Really, according to my wife, the student said "Stupid people breed" and then came up with the euphemisms to cover herself)

Even a cursory evaluation would discern many issues with a policy like that. Before any ethical concerns, the technology is just not there. Sure, we can chemically castrate human beings, male or female, but that is not without permanent ramifications (like being able to bear children down the road). The other option is surgical castration, which, again, is difficult to undo. Even if it were possible, this notion brings up the idea of liability for the United States (or the respective states if this is where it would happen) insofar as contingencies for adverse reactions. Can the government guarantee all temporary castrations will be done without harm to the person? Or can the government guarantee full fertility when breeding privileges are restored? What if something goes wrong? Can the person sue the government for damages?

Add to all of this the ethical consequences of this notion. Look at the value of the dollar in the United States. A person who was once a middle class worker may, by today's standard be considered lower-middle or upper-lower class. So, someone who may have been able to have children may be banned a year or two later. It is funny, because typically, the lower paying jobs - the jobs of the impoverished in this country - make the jobs of the rich easier, whether it is making their hamburger or moping their floors. If those people are helping society function, which empirically they are, why should they not be able to raise a family? How far would the United States be able to go in suffocating people's rights? (Do they not do that enough already?)

As a postscript, in regards to the United States being overpopulated: the infant mortality rate is up, as is the death rate as a whole, so I'm not sure that allowing children to be born any different than how it is today would matter.