1) BEIS DIN MAY NOT PROPOSE AN UNUSUAL ARGUMENT ON BEHALF OF ORPHANS
QUESTION: The Gemara cites a Beraisa that states that if a person stole an object and fed it to his sons, the sons are exempt from paying after their father (the thief) dies. If they did not consume the object and it is still intact, adult children are obligated to return the object to its owner, while minors are exempt. However, if the adult children say to the original owner, "We do not know what calculations our father made with you," they are exempt. RASHI (DH v'Ein) explains that the orphans are exempt because they claim that their father may have calculated the value of the stolen object already and paid the owner before he died.
The Gemara asks, why should this claim of the adult orphans exempt them from paying? Rashi (DH Mishum) explains the Gemara's question. Since the orphans admit that their father acquired the object by theft and that they are doubtful about whether their father paid back its value to the owner, their claim should be considered a Shema (uncertain) claim against the owner's Bari (certain) claim, and the rule is that a Bari claim prevails over a Shema claim. Why, then, does the Beraisa say that the orphans' claim exempts them?
Rava answers that the Beraisa should actually read as follows: If the adult sons say, "We know the calculations our father made with you, and he does not owe you anything," they are exempt (i.e. they make a Bari claim).
The Gemara here implies that the orphans are not believed with a Shema claim that their father could have made. However, the Gemara in Bava Basra (70b) states otherwise. The Gemara there states that in such a case, Beis Din may present on behalf of the orphans any claim that their father could have made if he was still alive.
The Gemara there states that if a "Shtar Kis" is presented against orphans, Beis Din argues on behalf of the orphans. This refers to a document which records that a person had deposited his item with the father when he was alive. The owner of the deposit demands the deposit back from the orphans. Beis Din counters on behalf of the orphans that the father may have returned it to before he died. Beis Din makes this claim because the father would have been believed -- with the logic of a "Migu" -- to claim that he returned the deposit. Since the father would have been believed to say that an Ones (unavoidable loss) happened to the deposit, he is believed to say that he returned it (when there are no witnesses who saw him steal it).
In the case of the Gemara here as well, Beis Din should be able to claim for the orphans what the father could have claimed had he been alive -- that he bought it from the owner after the theft. Why does the Gemara not recognize this as a valid claim which Beis Din can make for the orphans?
ANSWER: The ROSH answers that there is a difference between the case of the deposit in Bava Basra and the case of theft in the Gemara here. It is routine practice for a Shomer to return a deposit, while it is unusual for a thief to buy the object from the owner after he stole it. It is true that had the father himself claimed that he bought the object from the owner after he stole it, he would have been believed because of the "Migu" that he could have said that he never stole the object. However, since this is an unusual argument -- since a thief does not usually buy the object he stole from the former owner -- it is accepted only when the thief himself makes the claim. Beis Din will does not make such an unusual claim on its own initiative on behalf of the orphans.
(See the BA'AL HA'ME'OR (36b of the pages of the Rif), who also writes that Beis Din makes only probable claims for the orphans, not ones that are farfetched. See also the RAMBAN in Milchamos (as cited by the NIMUKEI YOSEF) who disagrees with the answer of the Rosh and Ba'al ha'Me'or.) (D. Bloom)

112b----------------------------------------112b

2) WHEN WITNESSES ARE ACCEPTED EVEN IN THE ABSENCE OF THE DEFENDANT
QUESTION: Rav Ashi says in the name of Rebbi Shabsai that Beis Din may accept witnesses even in the absence of the defendant. Rebbi Yosi bar Chanina says that Rebbi Shabsai refers to a case in which the defendant or witnesses are ill. RASHI (DH Cholim) explains that the witnesses are dangerously ill, and if the case would not be judged now it might never be judged. Alternatively, the case involves witnesses who planned to travel overseas. The Beis Din summoned the defendant to Beis Din but he did not appear. In extenuating circumstances such as these, Beis Din may accept the testimony of witnesses even though the defendant is absent.
The Gemara quotes Rav who says that witnesses may perform Kiyum for a Shtar even when the defendant is absent. Rebbi Yochanan disagrees and says that one may not perform Kiyum in the absence of the defendant. Rav Sheshes explains the source of Rebbi Yochanan's ruling. The Torah says discusses the law of an ox which has gored on three occasions (Mu'ad) and says, "... if its owner was warned (by witnesses) but did not watch it properly" (Shemos 21:29). This implies that the owner of the ox must come and stand next to his ox at the time Beis Din pronounces the ox to be a Shor Mu'ad.
If the law that Beis Din may not accept witnesses in the absence of the defendant is a Torah law derived from a verse, how can it be pushed aside simply because the defendant or witnesses are ill or the witnesses wish to travel abroad?
ANSWER: The RASHBA answers that the subject of the verse which discusses the law of the goring ox is in the category of Dinei Nefashos, laws of capital punishment, because the ox will be stoned to death if it killed a person. Only in cases of Dinei Nefashos does the Torah not permit Beis Din to accept witnesses when the defendant is absent. In contrast, in cases of Dinei Mamonos, monetary law, the requirement that the defendant be presents is only mid'Rabanan. Accordingly, when the Gemara quotes this verse as the source, it is not the actual source for this law in monetary cases but the source for the law in cases of life and death. Therefore, in extenuating circumstances such as illness, the Rabanan suspended their requirement that the defendant be present.
A similar explanation is given by the NETZIV in MEROMEI SADEH. He explains that the Torah's requirement that the owner be present when the witnesses testify that his ox is a Shor Mu'ad is a special law based on the verse, "if its owner was warned (by witnesses)...." This means that unlike an ordinary monetary case in which the owner's admission would suffice to obligate him, the ox becomes a Mu'ad only when witnesses testify in front of the owner. In all other monetary cases, witnesses do not fulfill any special role other than establishing the verity of the facts. Accordingly, the defendant would not need to be present if not for the enactment of the Rabanan that testimony be accepted only in the presence of the defendant even in monetary cases. (D. Bloom)