Gemara

(Mishnah): If Reuven was Menasech (this will be explained) b'Shogeg, he is exempt. If he was Mezid, he must pay.

(Rav): The case is, he poured Shimon's wine for a libation to idolatry.

(Shmuel): No, he forbade it by mixing it with wine that was offered to idolatry.

Shmuel exempts in Rav's case due to Kam Lei bid'Rabah Minei (one need not pay for damage done at a time when he becomes liable to die, e.g. for idolatry).

Rav holds that Reuven acquired (responsibility for) Shimon's wine when he picked it up. He is not Chayav Misah (liable to die) until he pours it to idolatry.

Bava Kama 70b (Mishnah): If Reuven stole and sold on Shabbos (he pays four or five).

Contradiction (Beraisa): He is exempt.

Answer #1 (Rami bar Chama): In the Beraisa, Levi (the buyer) told Reuven 'pick a date from my tree as payment for the stolen item'.

Rejection: Since Levi cannot force Reuven to give him anything (since Reuven is Chayav Misah for Chilul Shabbos), this is not a sale at all!

Defense (Rava): The Torah disqualifies an Esnan (a harlot's hire) for Korbanos, even when a man paid his mother for Bi'ah with her.

Beis Din cannot make him pay (since he Chayav Misah for the Bi'ah), yet if he pays, it is considered an Esnan. Here also, Beis Din cannot force Reuven to give the animal to Levi (for the date), but if he gives it, it was a sale.

Sanhedrin 72a (Rav): If a Ba b'Machteres (a thief tunneling into a house) took Kelim and left, he is exempt. (We assume that he was ready to kill the Ba'al ha'Bayis, so anyone could have killed him.)

(Rava): This is reasonable if he broke them but not if he took them! However, Rav exempts even if he took them!

Question (against Rava - Beraisa): If one stole on Shabbos and dragged it out he is exempt, for the liabilities come together (when he gets to Reshus ha'Rabim).

Answer: The Halachah is, he is exempt only if he threw it in the river.

Thieves tunneled into Rava's property and stole rams. They wanted to return them. Rava would not accept them, because Rav holds that they are exempt.

Rishonim

Rambam (Hilchos Chovel u'Mazik 6:7): If one poured another's wine to idolatry, he forbids it only if he owned part, or wantonly does idolatry. Even though he is Chayav Misah, he acquired the wine when he picked it up.

Hagahos Ashri (Bava Kama 7:6): Every case of Kam Lei bid'Rabah Minei is exempt, but one must pay to be Yotzei Yedei Shamayim.

Rashi (Bava Metzia 91a DH Rava): One who had Bi'ah with his mother must pay the Esnan he promised. Beis Din cannot make him pay due to Kam Lei bid'Rabah Minei, but b'Yedei Shamayim he must pay. Alternatively, if she seized it we do not make her return it. Therefore, if he paid it is considered an Esnan.

Shach (CM 28:2): The Or Zaru'a rules like Rashi. That is when one is liable, but we cannot punish him twice. However, when the Chiyuv is only b'Yedei Shamayim, e.g. damage through Gerama (causation), all agree that if the victim seized the money we make him return it. The Rivash (392 DH u'Mah) agrees. We do not pressure someone to pay a Chiyuv b'Yedei Shamayim.

Turei Even (Chagigah Avnei Shoham 10b DH Nefesh): Rashi holds that if the victim seized the money it is Vadai his, even to be Mekadesh a woman. If the transgressor took it back, we make him return it. Rava did not accept back his rams, for the thief is not obligated b'Yedei Adam, only b'Yedei Shamayim.

see Gilyon ha'Shas

Tosfos (Sanhedrin 72a DH Lo): Why didn't Rava accept his rams back from the thieves? B'Yedei Shamayim, they were liable to return them! We must say that they offered only because they thought that Beis Din would force them to do so).

Ketzos ha'Choshen (28:1): Rashi connotes that if one seized a debt owed to him b'Yedei Shamayim, we do not make him return it. The Maharshal says that this is only when he deserves a harsher punishment, but we do not administer it. What is his source? It seems that even when he receives the severe punishment, he must pay. However, Tosfos supports the Maharshal. If seizure helped, there would be no reason for Rava to return them! We must say that since a thief could have been killed in the tunnel, it is as if he transgressed with warning and fled. It is considered as if he received the severe punishment, therefore he is exempt even b'Yedei Shamayim. When he was not punished, and he is exempt only because we equate Shogeg and Mezid, he must pay to be Yotzei Yedei Shamayim.

Rashba (1:302): Rav Papa and the questioner in Bava Kama hold that Kam Lei bid'Rabah Minei exempts even b'Yedei Shamayim.

Or Some'ach (Hilchos Edus 12:2): Even though b'Yedei Shamayim, one is liable to pay for unobservable damage, when Kam Lei bid'Rabah Minei applies, he is exempt even b'Yedei Shamayim.

Poskim

Shulchan Aruch (CM 87:26): If Reuven claimed that Levi owed to him a Kenas, Levi does not swear Heses, for even if he would admit he would be exempt. If he claimed that he brought witnesses and Beis Din ruled that Levi owes to him a Kenas, and Levi denies this, he must swear Heses.

Bach (39 DH Kosav ha'Rivash): The Rivash (41) says that if Leah claimed that David vowed to give to her an Esnan, he must swear. This is difficult. Rashi (Bava Metzia 91a) exempts b'Yedei Adam one who transgressed Kares, due to Kam Lei bid'Rabah Minei. We assume that a woman who is Mezanah does not immerse for Nidah (Rosh 32:13), so he is exempt!

Rebuttal (Shach 58): Rashi discusses one who had Bi'ah with his mother, i.e. a Chiyuv Misah. All over Shas we say that the Halachah is unlike R. Nechunya ben Hakanah (who says that Kares exempts from payment), and the Poskim and Shulchan Aruch (350 and 380:3) rule unlike him.

Ketzos ha'Choshen (23): The Shach exempts from swearing about an Esnan promised to a married woman. Kam Lei bid'Rabah Minei exempts. However, if she claimed 50 for an Esnan and 50 for a loan, and he admitted to the Esnan, this is like partial admission of a debt. Rashi explains that it is a proper debt. It is like money owed by a powerful person whom Beis Din cannot force. Admission to other obligations b'Yedei Shamayim is not like admission to a debt, since he is exempt b'Yedei Adam. Kam Lei does not uproot the Chiyuv b'Yedei Adam; therefore, it helps to seize the money.