its got nothing to do with DNA but more to do with the legal presumption of fatherhood. its the presumption of guilt, and as it says extremely difficult to challenge. hope this explains it mentions it in detail so i cut and pasted bits as i quote
""Meanwhile, courts across the country are trying to redraw the legal lines of paternity now that genetic testing and welfare reform are colliding with 500 years of common law tradition, which has presumed that all children born in a marriage are the husband’s responsibility, whether or not he is the biological father. In May 2003, the New Jersey Supreme Court ruled that men who have admitted paternity, even if the mother lied to them, are not allowed to introduce DNA evidence to challenge support orders. Carnell Smith has been trying to push the issue to the U.S. Supreme Court, so far without success.
""
see the courts are biased and they dont want to hear dna evidence..
""I contact Child Support Services, and their whole thing is, ‘Take us to court. You don’t like what we’re doing, take us to court,’" he says. "Whether or not you’re the biological father doesn’t matter -- if someone’s got your name, and you’ve...failed to participate in the court date, then you have an obligation to pay child support, period."
Needless to say, taking DCSS to court is expensive (James says he’s already run up legal bills of $4,000), and success isn’t likely. To add insult to injury, even if you win, you won’t get any of your money back.""
""Considered in zero sum terms, any change that prevents some unjustly named fathers from supporting kids they didn’t sire reduces the amount of money children and single mothers receive while increasing states’ welfare payouts"" they dont care about the men, its all about the money they can raise
""But as long as state and federal laws remain as they are -- with low evidentiary thresholds for issuing paternity complaints, no proof of service required, the presumption of guilt in default cases, a series of short legal deadlines beyond which paternity becomes extremely difficult to challenge, and financial incentive for the government to keep naming dads and extracting money -- these cases will continue to come up.""