It actually seems pretty bizarre that a contract like this could be enforced in the first place. Since when was it possible to irreversibly consent to surgery? If someone sees new evidence against the procedure and decides against it they should be allowed to back out (or indeed have their child back out).
I didn't think of it that way... it is indeed odd why consent to surgery should be irrevocable even two years later. It seems like the mother should have power to withdraw consent.
By the way, to those who have faulted this woman as being stupid or unreasonable, I think that's being highly judgmental. First of all, we can likely assume that in the 3 years she's been raising this child he has not had any major problems with his foreskin. Given that a common reason for circumcision is the popular wisdom "if you don't do it, he will be hard to clean and get infections", then it makes perfects sense that she would be having second thoughts two years later.
Secondly, we have no idea how informed she was at the time of signing the agreement. Many parents in the USA often don't know a thing about circumcision until the time comes when they're forced to decide if their son should be circumcised. Many people in the USA have no idea what the foreskin is, or believe it is some mythical thing of evil that is constantly getting filthy and infected. It's also not unheard of for parents to be severely pressured by family, spouses or nursing staff to circumcise despite their gut instinct against it. I have read stories of this from both mothers and fathers.
Lastly, the situation with the father is quite ambiguous. The written agreement was that he was responsible for getting the son circumcised. Unless he was actively kept from doing so, I don't think it is unambiguously his "right" to force the issue in court two years later. If this is the case, then I think there is leeway for discretion by the judge. If that is so then yes, I do maintain that it is heinous of the judge to force foreskin amputation for a boy who has seemingly has lived 3 years without any medical problems with his foreskin, against the wishes of his mother.