It’s not an issue that comes up often but recently I had to deal with a parentage challenge where the father found out three years into his marriage that his daughter was not his. Ordinarily, the process would be to get a blood test to disprove parentage and therefore, he would be absolved of any financial responsibility. However, in this case, the statute of limitations for a blood test had passed already (2 years).
The general rule is that parentage is presumed (the formal term is conclusively presumed, although it is rebuttable, meaning it can be challenged – don’t ask, I don’t know why either) if the husband and wife are married at the time of conception. Not nine months before the conception, but at the time of conception. Again, doesn’t make much sense but I suppose it makes it easier for measuring and there’s less potential for abuse. It’s another example where efficiency trumps rationality.
Unless the father can either prove he was 1)impotent or sterile at the time of conception or 2) father requests a blood within two years of the conception, he is stuck being the father, whether or not any subsequent blood test proves otherwise. Furthermore, the blood test that is required needs to be done by a court expert and through a court filed motion by the father. Otherwise, he is pretty much shit out of luck.
It gets more complicated when a voluntary declaration of paternity is involved, but I will address that some other time. Also, if the Department of Social Services is involved, the requirements also are different. Suffice to say, this is a complicated area of the law, but the general rule itself can create some pretty unfair results.