Once parentage has been determined through DNA testing, can a court force the mother of the out of wedlock child to change the childs last name to that of the father?

First of all what would that PROVE?
Second the birth certificate is a legal document, but not infallible document ( scientific ). Name choice does not meaning paternity.

Nope. As @Tropical_Willie points out a name means nothing with regards to paternity.

Possibly… The father can petition for a name change and the mother could agree or disagree to the name change. If the mother disagreed, it would be up to the judge to decide if the name should be legally changed or not. I think it would be very unlikely for a judge to grant the name change against the mother’s will, but it could be possible depending on the exact situation.

So, while highly unlikely, it is possible for a judge to grant the name change based on the father’s petition depending on the situation. I think the father would have to have a really good reason for the name change though, especially if he doesn’t have any custody/visitation of the child.

I was just at family court last month where this issue just came up and it was a matter of the child either had to be an adult and requesting the name change or the the child was now living with the father and old enough to request the change with the court and the mother was not contesting the birth certificate name change. A certifided letter was sent to the mother that if she contested the name change to come to the next court hearing and proof was given to the court that she received it, she was called for at court, since she did not show up the name was changed to the fathers last name. So yes the name can be changed if not contested but not always.

I don’t see how the court could rule this way.

The court may allow this, if they were legally married.

Laws vary by state.

Examples:
Mississippi
Oregon

I do know of one case in Alaska. The child was removed from the mother’s home by the State and she terminated her parental rights. When the biological father petitioned for and was granted custody, the judge also granted a legal name change to the father’s.

Based on the above facts, no…the court cannot force such an outcome.

@laureth cites to the Mississippi statute which apparently defaults to the paternal surname unless the judgment declares otherwise. Further, it seems that a child who the parents want to be declared “legitimate” would have the paternal surname changed on the birth certificate.

However, none of that is by force, really.