Appeals courts in many states are refusing to allow genetic evidence in suits brought by husbands arguing they shouldn't pay child support. Instead, judges are falling back on an ancient doctrine known as "presumption of paternity."

• That rule -- which dates as far back as the Romans and then in English common law usage -- says that unless a man can prove he is sterile, impotent or had been away on the high seas -- he is the legal father of any child born to his wife during their marriage.

• The rule was intended to prevent husbands from attacking their wives' fidelity in court.

• The refusal to allow DNA evidence in such cases reportedly has the support of women's groups, but raises the ire of many men.

• Last December, the Pennsylvania Supreme Court affirmed a lower court ruling saying "family interests" outweigh the ordering of blood tests which might prove the contention of a Philadelphia man that he was not the father of his ex-wife's son.

Moreover, the U.S. Supreme Court refused to hear the case. In fact, it had rejected in 1989 a California man's effort to obtain DNA evidence that he was the biological father of a child born to his former lover and would therefore be entitled to visitation and other legal rights. Overturning California's presumption of paternity "would be destructive of family integrity and privacy," wrote Justice Scalia.

But men's groups have started lobbying legislatures in Pennsylvania, Michigan, Ohio and other states to change paternity laws. They argue that in this age of jet travel and in vitro fertilization, the presumption of paternity is antiquated.

Ironically, courts do allow states to use DNA evidence to establish paternity in cases where the man denies it.

Source: Margaret A. Jacobs, "Courts Favor Ancient Paternity Rule Over DNA Tests," Wall Street Journal, June 2, 1999.