My fiancee's ex boyfriend claims that he is the father of our unborn child. Now according to the conception date there is no way possible for him to be the father,but regardless in an attempt to get back at her he is demanding a paternity test when the child is born. Just curious to the rights that he has in demanding a test if she doesn't want to comply.

I'm not sure but, why doesn't she want to comply so she can laugh in his face or is she hiding something from you?

He can hire a lawyer and try to get an ordered paternity test if he has a reasonable claim to the child. He will have to pay for it all though, including the test and attorney's fees, and if he is the father will have to pay child support, etc..

If he strongly feel he is the Father of that child, then yes, he can ask for a DNA test. What happens if it comes back and he is the Father? Child support? Getting back together with his ex - your now fiancé? Petition for custody?