A CHILD BORN – when the mother is married or within 300 days of the end of the marriage (either by death or divorce) is presumed to be the child of the husband. The presumption can be challenged, but the challenger must prove that he is not the father by clear and convincing evidence.

A child born to an unmarried woman enjoys no such presumption. In those cases any man who hadsexual intercourse with the mother within 300 days
of the child’s birth may find himself in a paternityaction.

In cases to establish paternity and in cases in which a husband disputes paternity, science comes into play. The science of paternity has gone from very rudimentary to quite sophisticated during the past two hundred years.

In the 1800s eye color was used as a form of paternity testing. The paternity of a child whose eye color differed from the father’s was questioned. This was obviously not a very reliable indicator.

By the 1920s blood type testing became the scientific norm. Geneticists had discovered that blood types were inherited. Thus, a man whose blood type was not consistent with the child’s was eliminated as the father. A blood type consistent with the child’s, however, did not establish hispaternity. It simply did not eliminate him.

In the 1970s, HLA testing became the gold standard. This test, which compared proteins in the blood, was much more accurate in eliminating possible fathers. It often produced probabilities of between 80% and 90% that a man was not the father. Conversely, a man not eliminated was, to an 80% to90% probability, the likely father. Because this test required large blood samples, testing small children and babies was problematic. This often requireddelaying the test until the child was two years or older.

DNA testing is now the scientific norm. It requires specimens that are collected painlessly with a swab. Results are produced more quickly and they are far more accurate. They often exceed 99%. Since genetic material can be collected in so many ways, a small amount of amniotic f luid can be used to test for paternity even before the child is born. DNA test results are so accurate that, unless the test was improperly administered or a stand-in provided the sample, they are virtually impossible to refute.

DNA testing can sometimes yield unexpected results. In a child support case in Passaic County earlier this year, DNA testing revealed that the father of one twin was not the father of the other. The exceedingly fertile mother gave birth to twin girls of different fathers with whom she had had intercourse in the same week. He only had to pay child support for one. The paternity of the other twin is still not established.

Science and law are inextricably related. As science advances, the law must change. This is one area in which the law has kept pace with science.