Blood Tests and DNA – Part Three by Rabbi Chaim Jachter


Two weeks ago, we noted that the consensus view of twentieth century Dayanim is to reject blood tests as evidence that a husband is not the father of his wife’s child.  This approach was based to a great extent on the Gemara (Niddah 30a) that indicates that blood type is determined exclusively by the mother.  Last week, we examined four different rulings regarding the admissibility of DNA testing issued prior to the year 2000.  While Rav Ovadia Yosef rejected its admissibility to prove paternity, Rav Shlomo Zalman Auerbach accepts it as evidence of parentage.  Rav Shlomo Dichovsky approved of DNA evidence to a great extent, and Rav Yosef Shalom Eliashiv implied his acceptance.

This week, we shall discuss the admissibility of DNA evidence in identifying the remains of a missing husband.  This emerged as a major issue in the aftermath of the World Trade Center terrorist act, which sometimes left DNA evidence as the only possible way to identify the remains of a missing husband (as we discuss in Gray Matter 2:121-123).  Our discussion of this issue is based largely on Rav Mendel Senderovic’s discussion in Teshuvot Atzei Besamim (number 16) that presents fine arguments to support the unequivocal ruling of Rav Zalman Nechemia Goldberg that DNA is admissible evidence to identify the remains of a missing husband.   

DNA Evidence vs. Blood Tests 

Rav Mendel notes that only blood tests seem to have a passage in the Gemara that precludes their use in determining paternal identity.  The same Gemara notes that the father contributes the material that produces the bones and fingernails of the child.  Thus, argues Rav Mendel, a DNA sample may be taken from bones and fingernails in order to determine paternal identity (the Haifa Beit Din, cited in Assia 35:47, also drew such a distinction).  Although there is no precedent in the Gemara that is analogous to DNA identification, there are no counter-indications that preclude its use. 

In addition, the skepticism that Rav Waldenburg expressed in regards to scientific evidence (cited two weeks ago) seems not to be relevant to DNA identification of a missing husband’s remains.  DNA identification is based on the assertion that no one (save for identical twins) has the same DNA.  Rav Mendel notes that this has been proven with empirical evidence regarding more than a million individuals.  Accordingly, skepticism about the accuracy of DNA testing appears misplaced by the year 2001 in light of the overwhelming amount of evidence supporting its accuracy.  We may add that DNA evidence has withstood vigorous challenges from defense attorneys in civil courts throughout the western world. 

Can we Devise Simanim? 

Some have pointed out that the absence of a Talmudic precedent for DNA testing automatically precludes its use as a new means of identifying individuals.  A proof for this might be derived from the Chatam Sofer (Teshuvot Orach Chaim 207, cited in the Mishnah Berurah 648:65; however, the Chatam Sofer appears to have changed his mind about this issue, see Teshuvot Chatam Sofer O.C. 183, also cited in the Mishnah Berurah ad. loc), who rules that we may not rely on the Simanim (means of identification) devised by many Acharonim (cited in the Mishnah Berurah ad. loc.) to determine if an Etrog is a hybrid (Murkav).  The Chatam Sofer explains that the problem with these Simanim (such as bumpy skin and an indented stem) is that they do not appear in the Gemara.  One could claim that DNA evidence may also not be relied upon since it also lacks a Talmudic source. 

One could respond to this argument in a number of ways.  First, many Acharonim do endorse relying on Simanim to prove that an Etrog is not Murkav.  Second, the Gemara (in the third chapter of Masechet Sukkah) discusses the Halachot of Etrogim in considerable detail, and the absence of certain criteria for determining the status of an Etrog might imply a rejection of such Simanim.  One could counter, though, that the Gemara does not address lemons (the only fruit that could be crossed with an Etrog to produce a realistic looking hybrid) because they were first encountered in the time of the Rishonim, (see my Gray Matter 2:35-40). 

Moreover, Rav Senderovic notes the Gemara in Chullin (64a) that discusses Simanim to identify eggs as the product of kosher birds (such as having the yolk on the inside and the albumin on the outside).  According to Rashi, the Gemara rejects the use of these Simanim (ad. loc. s.v. Hachi Garsinan) because we do not have a tradition emanating from Sinai that such Simanim constitute legitimate evidence of Kashrut.  Rabbeinu Tam (cited in Tosafot ad. loc. s.v. Simanin), on the other hand, explains that it does not constitute adequate evidence because of the counterevidence of the eggs of a raven (a non-kosher bird), which have the Simanim of the eggs of a Kosher bird.

The Ramban (ad. loc. s.v. Hah) combines the reasons of Rashi and Tosafot, explaining that we do not rely on these Simanim for eggs because of both the counterevidence of the ravens’ eggs and the lack of a tradition from Sinai.  Rav Senderovic argues that since after years of testing more than a million people we have not found two individuals (other than identical twins) with the same DNA, we may rely on DNA as a Siman to identify the remains of a missing husband since there is no counterevidence to question its accuracy.  Rav Senderovic also notes that Rashi seems to imply that this is a specific exclusion that applies only regarding eggs and is not a principle that applies to all Halachic realms.  

Most important, Rav Zalman Nechemia and Rav Mendel note, is the precedent of Poskim relying on finger prints (see Otzar HaPoskim 17: list of Simanim number 62) to identify the remains of a missing husband.  DNA evidence is entirely analogous to finger prints, argue Rav Zalman Nechemia and Rav Mendel, so DNA evidence, like fingerprints, should be reliable evidence to identify the remains of a missing husband.   

Random Sampling 

Some have questioned the efficacy of DNA on the grounds that not every human being alive has been tested to determine if everyone has different DNA.  They argue that science has proven only that the over one million people it has tested do not have the same DNA.  This does not constitute adequate evidence according to some.  Rav Zalman Nechemia responds that when Chazal made determinations, such as the assertion that a majority of animals do not have a blemish that renders them a Tereifah (thus permitting us to drink the milk of animals that have not been examined for Tereifot), they reached their conclusions based on random sampling.  Rav Zalman Nechemia finds it counterintuitive to maintain that Chazal traveled throughout the world and inspected every animal to reach this determination.  We should note that although Rav Zalman Nechemia does not marshal evidence for this argument, the intuition of an eminent scholar has credence (similar to Rashi’s intuition regarding the Eiphod worn by the Kohen Gadol, see his commentary to Shemot 28:4 s.v. VeEiphod). 

Rav Mendel suggests that one could respond that perhaps the assertions made by Chazal are derived from divine sources and therefore constitute impeccable evidence despite their reliance on random sampling.  Rav Mendel rejects this line of thought, noting the Gemara (Chullin 47a) that records an incident in which Rav Ashi thought to classify an animal as a Tereifah because of what he perceived as an abnormality.  However, Rav Huna Mar Bar Avya told him that all of these rural or healthy animals (Rashi ad. loc. s.v. Boryata presents these two alternate explanations) have this abnormality and the butchers are very familiar with it and even have a name for it.  The Gemara gives Rav Huna Mar Bar Avya the last word, indicating that Rav Ashi accepted his critique. 

We see from this passage that Chazal made at least some determinations based on their experiences with a random sample of animals and did not conduct an investigation of every animal in the world to reach their conclusions.  We might add that the efficacy of the scientific methodology of random sampling has been proven repeatedly throughout the world in the past century, leaving us no reason to reject its application to the Halachic realm (similar to Rav Shlomo Zalman Auerbach’s comments justifying the use of DNA evidence that we cited in our previous issue).   

Combination of Inadequate Simanim 

Rav Mendel notes that some have argued that DNA testing constitutes inadmissible evidence based on the fact that its conclusions are based on the combination of thousands of sub-factors which individually constitute inadequate evidence.  They cite the ruling of the Rama (Even HaEzer 17:24, see my Gray Matter 2:120-121) that many inadequate Simanim may not combined to constitute one adequate Siman.  Rav Mendel responds that one views the thousands of sub-factors as one whole unit, which undoubtedly constitutes adequate evidence (a Siman that is unique to fewer than one of a thousand people constitutes an adequate Siman to identify the remains of a missing husband, as noted by the Beit Shmuel 17:74; the possibility of someone having the same DNA ranges from ten billion to one to one quintillion to one). 

As precedent, Rav Mendel cites a ruling from the Mahari (Teshuva number 239, the source of the previously mentioned strict ruling of the Rama) that one may combine the fact that the missing husband’s remains showed that he was blind in an eye and that he had a scar above that same eye to constitute an adequate Siman (also see Pitchei Teshuva E.H. 17:107).  Similarly, the Mishpatim Yesharim (number 39) rules that we accept a tooth that is cracked, protrudes and has a black spot at its edge as an adequate Siman.  Just as we view the eye and the tooth as constituting one unit which has more than one feature (and we do not view each identifying mark individually), so too we view DNA conclusions as constituting one Siman even though they are created through a combination of many sub-factors.  Moreover, it is even more compelling to view a person’s DNA as constituting one individual unit of evidence since the sub-sections of DNA are integrally related to each other.  As support for his contention, Rav Senderovic once again cites the precedent of Poskim relying on fingerprints as an adequate Siman, as fingerprints prove identity by combining the strands from the entire fingerprint. 


There is no compelling reason to reject the use of DNA evidence to identify the remains of a missing husband, especially since it is exceedingly accurate.  Indeed, contemporary Poskim rely on DNA to prove the identity of the remains of a missing husband to some extent or another, as we shall discuss next week.  We shall (IY”H and B”N) conclude our series next week with a discussion of the problem that DNA evidence could potentially reveal the identity of Mamzeirim.

Blood Tests and DNA – Part Four by Rabbi Chaim Jachter

Blood Tests and DNA – Part Two by Rabbi Chaim Jachter