Actually, your son should be talking to the attorney, paying for the attorney, paying child support, etc. This is a legal situation between the parents.

<<<I also know there is some form in the US passport office that a parent can fill out so a passport will not be issued to a child, and the child will not be taken out of the country. >>>

that's true, IF the father has rights at all. That's why a lawyer specializing in custody matters is needed. It's not clear whether the father is named on the child's birth certificate, or has somehow asserted legal rights.

Just because the child is a US citizen by birth doesn't mean it isn't also a Philippines citizen. Maybe the child already has a Philippines passport. In which case the mother could leave with no one stopping her for any reason.

Do read clarkgriswold's post - excellent advice.

You also need to consider the Philippines requirements for citizenship. If its like the US, the mother may be able to file with the Philippine consulate and have the child declared a Philippine citizen and the child would then have a Philippine passport to leave the country. Just because the child is an automatic US citizen by virtue of being born here, doesn't mean that the child is not entitled to citizenship in some foreign country.

Just a quick google search leads me to believe both hetismij and williamscb13 are right that the mother can obtain a Philippines passport for the baby. Again, whether she can leave the country depends on the father's "interest" -- i.e. whether he has legal rights to stop her from leaving, which none of us really knows (the facts or the law)