Rambam - 1 Chapter a Day

I.e., the laws apply with regard to both movable and landed property.

The Tur (Choshen Mishpat 37) quotes two opinions: one which maintains that this law applies even when Shimon merely suspects that Reuven stole from him, and the other that it applies only when he is certain of the matter.

E.g., testifying that Yehudah’s witnesses are unacceptable or the like.

I.e., he will bring witnesses who testify that Reuven stole it from him.

Since he prefers having the property remain in Reuven’s possession, he is considered as having a vested interest in the matter and is disqualified from testifying.

But not the garment, for this law does not apply with regard to movable property as stated in the following halachah. Landed property can never be stolen, but instead remains in the possession of the legal owner even when it is not in his physical possession. Hence the original owner is always expecting to receive his property (Bava Batra 44a and commentaries).

I.e., since Levi assumes the position held by Reuven. The same laws which apply with regard to testifying on behalf of Reuven apply with regard to testifying on his behalf.
From Bava Batra 43b, it appears that “it is more comfortable for him...” means that the claimant is a difficult person while the heir or the purchaser is easier to deal with and will surrender the property more graciously. There are some who also use this same explanation in the first clause. The Rambam, however, does not, because it is highly unlikely that it will be “more comfortable” for the owner to deal with the thief than with the claimant (Radbaz).

According to the Rambam, it does not matter whether the sale precedes the legal Owner’s despair that the article will be returned to him or whether he despaired afterwards (Hilchot Geneivah 5:3). Many Ashkenazic authorities differ. See Sefer Me’irat Einayim 37:48.

As the Rambam proceeds to explain, he.is not considered as having a vested interest in the matter, because the garment will never be returned to him.

See Hilchot Geneivah 5:3, Hilchot Gezeilah 5:7, where this concept is explained. A thief himself can never acquire the stolen article while it remains in the same state as when it was stolen. And if its owner never despairs of recovering it, another person may also not acquire it. If, however, the owner despairs of recovering it and the thief sells or gives it to another person, that other person acquires the article. The thief is required to reimburse the owner for the article, but the article itself remains in possession of the person who acquired it.
The Shulchan Aruch (Choshen Mishpat 37:17) clarifies that in Talmudic times, this ruling applied only when the thief did not leave any landed property in his estate. If, however, he left landed property, that property is on lien to his debts. Hence, there is still a possibility of the original owner recovering the value of the object stolen from him. Accordingly, he is considered as having a vested interest. Moreover, in the present age, we follow the ruling of the Geonim who maintain that even movable property left in a person’s estate is on lien to his debts. As such, as long as the thief leaves any estate whatsoever, the person from whom the property was stolen is considered as an involved party.

I.e., as long as they do not receive the stolen article itself as an inheritance, the thief’s heirs are under no responsibility to the owner of the stolen article.

As long as the article itself is in the heir’s possession, they must return it to the original owner. Inheritance - in contrast to purchase - is not considered as a change of domain. Instead, the domain of the heir is considered as an extension of the domain of the thief (Bava Batra, loc. cit. and commentaries).

I.e., Reuven had a clause included in the contract of sale, stating that he does not accept any responsibility if the field is expropriated from Shimon the purchaser. Even if the field is taken because of a legitimate claim for which he would ordinarily be responsible, he is freed of liability because of this clause. See Hilchot Mechirah 19:3.

I.e., Yehudah claims that Reuven purchased the field from a thief before selling it to Shimon [Tur (Choshen Mishpat 37)].
The Tur and the Ramah (Choshen Mishpat 37:15) emphasize that if Yehudah’s claim to the field would be effective only against Shimon the purchaser and not against Reuven, the seller, Reuven is allowed to testify on Shimon’s behalf. For his creditor would have the right to expropriate the property from Yehudah, just as he could have expropriated it from Shimon.

E.g., by disqualifying Yehudah’s witnesses.

Cf. Psalms 37:21. I.e., if the field is taken by Yehudah, it will not be able to be used as security for his debt. Reuven will not have such feelings if the field is expropriated from Shimon, for he can tell Shimon that by selling the field to him without accepting responsibility, it was as if he informed him of the likelihood that it would be expropriated from him.
The above applies provided Reuven does not possess another field of equivalent value in his own possession. If, however, he possesses another field, that field will be expropriated by a creditor and not the field that was sold previously. Hence, it will make no difference to him whether or not Yehudah expropriates that field. As such, he is acceptable as a witness (Kessef Mishneh, based on Bava Batra 45a and commentaries).
The Merkevat HaMishneh differs and maintains that the Rambam follows the approach of his teacher, Rav Yosef Migash who interprets the above passage as implying that even when the seller possesses another field, he is disqualified as a witness. This view is quoted by the Sefer Me’irat Einayim 37:37 and the Siftei Cohen 37:22.

I.e., movable property. This also refers to an instance where Reuven did not accept financial responsibility for the sale [Shulchan Aruch (Choshen Mishpat 37:16)]. There are those who maintain that this is not necessarily the Rambam’s intent, but the Siftei Cohen 37:25 cites Hilchot Mechirah 19:3 as indication that it is.

In this instance as well, Yehudah claims that Reuven purchased the article from a thief and Yehudah was the rightful owner [Shulchan Aruch (Choshen Mishpat 37:16)].

I.e., as above, he testifies to disqualify the witnesses Yehudah brings.

In contrast to landed property which remains in the same place and therefore its ownership is a matter of public knowledge, movable property can be transferred from hand to hand and is not as identifiable. Accordingly, our Sages did not consider it on lien to a person’s debts. For if a creditor could expropriate movable property from a purchaser, no one would purchase such property, for they would always be afraid that it could be expropriated (Bava Batra 44b and commentaries).

I.e., it was specifically stated that this movable property would be used to pay the debt. Even if a contract included such a clause, the clause is not valid and the purchaser may maintain possession of the movable property. See Hilchot Malveh V'Loveh 18:5.
Since Reuven's creditors may not expropriate the property from Shimon, Reuven has no benefit in the property remaining in Shimon's possession Hence, he is allowed to serve as a witness on his behalf (Kessef Mishneh).

Therefore even if Yehudah's claim prevails and the property is expropriated from Shimon, Shimon does not have a claim against Reuven. For Shimon acknowledges that Reuven had the right to sell the property to him.
The Shulchan Aruch (Choshen Mishpat 37:16) does not mention this point in his statement of the law. There are commentaries that explain that since the Shulchan Aruch mentions that one does not accept responsibility, this point is not necessary. The Siftei Cohen, however, differs and maintains that the practice cited by the Shulchan Aruch is not followed in all places. In the places that did not accept that practice, even if the seller does not accept responsibility, the purchaser must recognize that the property is his.

According to the opinion that the Rambam is speaking about a situation where Reuven the seller accepted financial responsibility, the clause is understood simply: He is considered as having a vested interest, for if his testimony is not accepted, the purchaser will sue him for the value of the property and he will have to make restitution.
According to the view that the seller did not accept financial responsibility, he will not be held liable if the seller sues him. Nevertheless, he is considered as having a vested interest. For no person desires that the to whom he sells property have complaints against him and call him to court because of them [Bayit Chadash (Choshen Mishpat 37)].

For then the factors which the Rambam mentions in the following clause are not relevant.

As the Rambam writes in Hilchot Malveh v’Loveh 18:2, a lender may place all of his movable property on lien to a debt by stating in the promissory note that he establishes this lien by virtue of the establishment of a lien on landed property. Moreover, he can include a stipulation that the lien will also include all movable property that the debtor will acquire in the future.
The Shulchan Aruch (Choshen Mishpat 37:16, 60:1) states that in the present age, the Rabbis invalidated both these stipulations and do not allow a lien on movable property at all. According to this view, the seller is allowed to testify, even if he once owned landed property. The Siftei Cohen 37:26, 60:4, however, differs and maintains that such stipulations are valid even at present.

Hence he is considered to have a vested interest, as stated in Halachah 3.

I.e., the disqualification of witnesses for having a vested interest is not a cut and dry matter, conforming to set rules. Instead, it is one which a judge must think over, considering all the possible ramifications.

The Kessef Mishneh states that a person is disqualified for having a vested interest only when his testimony appears to advance that interest. If he testifies against his own interest, his testimony is accepted, just as we accept the acknowledgment of liability of a person sued with owing a debt.

See Hilchot Sanhedrin 23:3 which elaborates on the care a judge must show with regard to having a vested interest in a case.

I.e., needless to say, the judges may not be transgressors. Nor may they be related to the litigants, the witnesses, or to each other (Kessef Mishneh). Similarly, all of the factors mentioned in Chapter 9, Halachah 1, disqualify a judge.

A court of 23 judges.

Israel’s highest court.

Hilchot Kiddush HaChodesh 4:9-10.

The first three judges who make the fundamental calculations with regard to the declaration of the leap year may not be related (Lechem Mishneh).

For we fear that their love or hate of the principals may influence their subconscious thinking process. As mentioned in Chapter 13, Halachah 15, we do not suspect that a person will consciously transgress and deliver false testimony on behalf of a colleague. Similarly, we do not believe that a person will willfully deliver a wrong judgment because of his feelings for or against a particular individual. Nevertheless, there is the possibility that without knowing, his feelings will influence his decisions.

For a judge is not acceptable until his mother is a native-born Jewess, as stated in Hilchot Sanhedrin 2:9, 11:11. These individuals are, however, acceptable as witnesses.

For we suspect that because of the judge’s age or because the eunuch never had children, they will have cruel tendencies and will not be merciful (Hilchot Sanhedrin 2:9).

For judges who adjudicate cases involving capital punishment must be fit to marry into the priesthood and they must have no physical blemishes (ibid. 2:9, 11:11).