Excellent Buzzfeed piece here. The basic idea is that a non-profit org offers drug addicts cash payments in exchange for sterilization or long-term birth control. This isn't the first time I've encountered this. A similar program was offered in King County, WA for a bit before it got shut down in the early 2000s (or was it Tacoma? I can't quite recall).
I don't have too much to add here. I tend to side with Julian Simon on this one: people are a net benefit. I also tend to think folks should have children when they've made a clear, rational decision to do so. Sterilizing drug addicts suggests that some people think there is a close to zero probability that such a rational decision is possible, at least for addicts.
Cash for a tubal ligation is voluntary. Because of BATNA disparity it is not euvoluntary. Is this exchange ethical? Should it be banned? Is it appropriate to consider the welfare of the not-born when conducting cost-benefit analysis?