NickD JD – I’d love to know what case you’re talking about. Seriously! If you can remember which was it was please edit and add that info. I’d love to read it.
Personally, I am not aware of a US Supreme Court Case which has stated that there’s an *irrebuttable* presumption that the husband is the natural father of a child conceived during a marriage (there was years ago before dna test, but now laws have been revised somewhat). Paternity can be rebutted with conclusive evidence (dna test), but there are specific guidelines. For example, in the state of CA it can be rebutted *only* by the husband or the wife and only within the first two years of the child’s life.
But, to get back to the original question… Is there any legal action that your Dad can take against the biological father?
Many men have tried filing suit against the biological father to recover financial expenses they’ve paid for the child…and they've been unsuccessful.
He should talk to a local attorney, but in all likelihood the answer will be “you’ll be wasting your time and money”
Now, if he intends to file for divorce, he can contest paternity during the divorce proceedings and IF THE COURT ALLOWS paternity to be contested / disestablished (and they very well may not allow it on the basis that he’s waited too long / it’s not in the best interest of the children), then he can avoid being ordered to pay child support. But he needs to realize that he will then have no legal rights to these children—so no visitation. I assume he loves them and they love him, so is he willing to have the children yanked out of his life? And is he willing to do that to the children (the emotional damage it could cause to them could be HUGE)? Personally, I wouldn’t, but that’s just me.
On the other hand, if they are already divorced, there are a few states--and it’s *very few*--that will allow him to go back and contest paternity / be relieved of child support (again, with no visitation rights). But in the majority of states, if he fails to contest paternity during the divorce proceedings, he’s barred from going back and contesting it at a later date.
Of course, I say all that assuming you live in the US. If you don’t live in the US, then the laws may be totally different in your country.