BLOOD TESTS AND PATERNITY
By W. J. BROWN
THE practical application of blood tests to the problems of paternity has long been discussed in medico-legal circles and the second reading of Lord Merthyr's Bill in the House of Lords earlier this month has brought the matter one step nearer to the Courts.
It is well to be quite clear as to the extent of the Bill. Pater sem per incertus, said the Romans ; and so he still is. No blood test can establish paternity—that is to say, no man can be proved to be the father of a child. But a test can prove that in some cases a certain man cannot possibly be the father. The result of a test can never be positive in the present state of medical knowledge, but it may be nega- tive or it may be inconclusive. An inconclusive result, namely that the man might be the father of the child, can do no harm even if it does no good. It is in the negative finding that the value of the test lies.
It has for some time been known that human blood was divisible into various groups, and that individuals varied as to the group to which they belonged. It has further been proved that the characteristics of the blood group to which a child belongs are transmitted by its parents. If, therefore, a child is found to possess a characteristic which neither the mother nor the reputed father possesses, then the real father must be sought elsewhere. The blood group system may thus be shortly explained. There are two main groups known as A and B. About 57 per cent. of people have blood belonging either to group A or to group B, or to a combina- tion known as AB. Those whose blood is neither A, nor B, nor AB, are primarily classed in group 0. Neither the-A nor B factor can appear in a child unless it is present in one or both of the parents, and similarly the 0 factor cannot be present in a child whose parents are a combination of A and B, neither can 0 parents produce children with any of the A or B factors. There is a further check in factors known as M and N, which are present either singly or in combination in every person. So that in any case of dis- puted paternity it is possible to put the blood groups of the two " certainties," the mother and the child, into one column, and before any test is made on the putative father, to put into a second column all the combinations to which he might belong, and in a third column all those to which he could in no circumstances belong. If he is among the groups in the second column that means he might be the father as well as hundreds of thousands of others of his group. If he is in the third column he has been unjustly accused. It will be obvious that if when the blood groups of the mother and the child have been ascertained it is seen that the child's group can be accounted for by the mother, there is no purpose in testing the father, because the result in such a case cannot be conclusive.
The next and obvious query is the proportion of cases in which a useful result is obtainable. That is to say, having ascertained the groups of the mother and child and placed them in column one, how often will an analyst be able to place an innocent man in column three? The answer is scientifically accepted as about one in three. Continental estimates show that in all contested affiliation cases the blood test would exonerate about 20 per cent. of the putative fathers, but British estimates are about 12 per cent. This shows how high is the percentage of men in these cases (35-40 per cent.) who are in fact innocent.
It might not be worth going to the trouble of introducing legislation to make these tests compulsory if it were not generally realised how very unsatisfactory is the evidence offered in affiliation cases. It is easy enough for a woman who finds herself pregnant to attempt to fasten the respon- sibility on a man who is earning a steady wage, or another who is rich enough to pay to keep his name out of the papers. The corroborative evidence which the law requires can be supplied by her family, and it is very hard for a man to establish an alibi on a particular occasion a year ago. If he cannot, there is only his word. Objective evi- dence is most desirable.
There is nothing illegal about blood tests as the law now stands. They have been given in evidence, and given suc- cessfully from the man's point of view. But there is at present no compulsion to submit to them, and a woman's legal adviser must in duty bound hesitate to advise her to submit to a test which cannot help her case and may destroy it. The Bill gives the Court power to order a test to be taken if it thinks proper, and gives either party the right to demand one. If the mother refuses the test her case would be dismissed. To check frivolous applications, the Court may order the party applying for a test to pay the costs of it. Otherwise the Court may order the costs of the test to be paid out of public funds, that is to say the same fund which pays the expenses of poor persons in the Courts. This provision is very necessary, for otherwise it would be a denial of justice if a rich man could always demand a test and pay for it, whereas a poor man (the vast majority in cases of this kind) would be deprived of aid merely because he could not afford it.
Various objections have been raised to blood tests. It has been said that the cost would be prohibitive. There are, in round figures, about 5,000 applications for affiliation orders in a year. About i,000 applications fail, and in the great majority of the remainder paternity is admitted, or not seriously contested. It is improbable that there would be more than 500 cases a year where it would be necessary to order the test. The cost is about £5 in each case, and might well be less when the system was organised. £2,500 is not a great sum to pay for the improval of justice.
Much has been made of the difficulty of these tests. The actual obtaining of the blood samples can be done by any doctor in a few moments by drawing two or three drops of blood from the finger, and the " operation " is painless and leaves no trace. There are pathologists at any labora- tory or big hospital who can make the analysis when the necessary serum is available, and the samples can be sent by post. But the centres where analysis is carried out would for convenience' sake be narrowed to one or two.
Another problem has been raised of what should be done with the evidence if it were found to be inconclusive —that is to say if the man's blood group fell in the second column, and he might, or equally well might not, be the father. It was thought that if the Court were told that a test had been taken and that the man might be the fathstr, improper conclusions might be drawn, and so it was at one time considered that no evidence of the test should be given. In New York, where these tests are frequently taken, the law was altered to this effect; but there such cases come before juries, who are more easily influenced, whereas in this country they come before magis- trates. But it was eventually decided that the result of an inconclusive test should be reported to the Court, but that no comment should be made on it by either party.
It is at first sight a drawback to the Bill that the result of a test which the woman would have to undergo could not be to her advantage, and might very well destroy her case. But to oppose the Bill on those grounds is mis- placed chivalry and woolly-headed sentiment. If the woman has a true claim the test cannot harm it. If she has a bad one every possible evidence should be admitted to expose it.
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