Gemara

(R. Yehoshua ben Levi): Semichah does not apply in Chutz la'Aretz.

Suggestion: Fines cannot be judged at all in Chutz la'Aretz.

Rejection (Mishnah): We establish Sanhedriyos in Eretz Yisrael and Chutz la'Aretz.

Rather, he teaches that we do not give Semichah in Chutz la'Aretz.

46a (Beraisa - R. Eliezer ben Yakov): I heard that Beis Din can lash or punish unlike Torah law. They do not intend to change Torah law, rather, to make a fence (to deter transgressors). Once, in the days of the Yevanim, a man rode on a horse on Shabbos and Beis Din killed him. Once, a man had Bi'ah with his wife under a fig tree, and Beis Din lashed him.

These people did not deserve to be killed and lashed, but at the time it was necessary.

Gitin 44a (Reish Lakish): If Reuven sold a work animal to a Nochri, we fine him. He must redeem his animal, even for 100 times the sale price.

Bava Kama 96b: A case occurred in which a man stole a yoke of oxen. He plowed and seeded with them, then returned them.

Rav Nachman: Evaluate the increased value (the owner receives it).

Rava: Are the oxen the only cause of the increased value, and not the land?!

Rav Nachman: I meant that the owner should receive half.

Rava: Still, the stolen object returns intact, like the Mishnah says 'all thieves pay as at the time of the theft'! (Why should the owner profit?)

Rav Nachman: Rav Huna says that I and Shmuel are brothers in judging! This man has stolen many times, so I want to fine him.

Rishonim

Rif (Gitin 23a): Reish Lakish taught that if one sold a work animal to a Nochri, we fine him and force him to redeem it, even for 100 times the price. A Gaon says that this is only in Eretz Yisrael, but we do not collect fines in Bavel.

Rebuttal (Rosh Gitin 4:41): This is unrelated to the rule that we do not collect fines in Bavel! That is because we require Mumchim, and Semichah is only in Eretz Yisrael. If Chachamim enacted fines to make a fence for Torah, why shouldn't they be collected in Bavel?!

Gra (CM 1:25): The Mordechai challenged the Rif from the teaching of R. Eliezer ben Yakov and Rav Nachman and the Reish Galusa (who imposed fines in Bavel). The Rif agrees that a Chacham in Chutz la'Aretz may make a fine if necessary. He says that in Bavel we do not collect fines that are for all generations.

Rif and Rosh (Bava Kama 34a and 9:5): Rav Nachman was in Chutz la'Aretz. This teaches that even in Chutz la'Aretz we may impose such fines. R. Eliezer ben Yakov taught that Beis Din may fine greater than Torah law.

R. Efrayim: We fine for the insult to Hash-m. For Kavod ha'Briyos we do not fine more than the Mishnah says.

Yam Shel Shlomo (Bava Kama 9:7): The Rif does not say 'such' fines to exclude bodily punishment, for R. Eliezer allows this. Rather, he teaches that the fine must be reasonable, just like Rav Nachman fined only half because the land also helped produce half the increased value.

Rosh (ibid.): Stam judges cannot impose fines above Torah law. This is only for a Gadol ha'Dor like Rav Nachman, who was the Reish Galusa's son-in-law, or someone appointed to judge by the Nasi or Tuvei ha'Ir that the Rabim accepted on themselves. Some say that this applies even to a Beis Din of three commoners.

Rambam (Hilchos Gezeilah 3:6): If a man stole an animal and used it to plow and returned it, he need not pay because he did not cause a loss or weaken it. If the man is Muchzak to steal or extort or do such things repeatedly, we fine him, even in Chutz la'Aretz.

Rambam (Hilchos Sanhedrin 24:6): A judge can always make a person's property Hefker or deprive him of his rights if he sees that this will fence breaches of Torah and strengthen it. It says in Ezra "whoever will not come... by the counsel of the officers and Chachamim, his property will be made Cherem". This teaches that: Beis Din has power to make Hefker.

Kesef Mishneh: The Rambam says always to include nowadays.

Poskim

Shulchan Aruch (CM 2:1): Any Beis Din, even if it is did not get Semichah in Eretz Yisrael, if it sees that people are Perutzim about (wantonly transgress) a matter (and it is necessary at the time), they can impose death or any other punishment, even if there is not full testimony.

Bedek ha'Bayis (citing Rikanti citing Zohar Mishpatim 112): A judge who is meticulous to acquit Resha'im will die before his proper time. Beis Din should punish more than the Torah says to make a fence for Torah!

SMA (3): Even if an individual is Parutz, Beis Din can punish him as they see fit. When the nation is Parutz, they can enact to punish everyone who transgresses, even one in whom they did not see Peritzus.

Shulchan Aruch (ibid.): (They can make his money Hefker or destroy it, according to what is needed to correct the generation). All their actions must be l'Shem Shomayim. Only the Gadol ha'Dor may do so, or Tuvei ha'Ir (the governors of the city), if Beis Din authorized them.

Beis Yosef (DH uvi'Teshuvah): A particular debtor gave his property to a minor to prevent his creditor from collecting it. The Rashba (2:360) said that it is proper for Beis Din to make a fence against such Peritzim, lest others do similarly. They can do so, for Hefker Beis Din Hefker.

Beis Yosef (DH v'Chasuv): The Rashba (Teshuvah 59 attributed the the Ramban) says that if a Tzibur enacted that anyone who does not bring (within a specified period) his proofs of what he is entitled to, will forfeit them, it should not apply to one who was away and did not hear the announcement. The Tzibur can agree that it will apply in every case, and even to orphans, if this will help silence complaints.

Beis Yosef (55 DH veha'Rashba): The Rashba (3:60) says that a Beis Din can make money Hefker only if it has power. The Magid Mishneh (Hilchos Mechirah 11:13) says that the Rashba does not require Semichah, as long as they are experts who judge the Rabim. The Nimukei Yosef (78a DH Gemara) says that it is one who can judge monetary cases alone, like it says in Nedarim.

Bach (DH v'Chosav): The Tur connotes that the Rif allows even a Gadol ha'Dor to fine above Torah law only if the Rabim appointed him. However, R. Yerucham says that the Rif does not require that the Rabim appointed him. This is the primary opinion.

Yam Shel Shlomo (ibid.): A Gadol ha'Dor cannot fine by himself unless he is expert in Hora'ah. This is why Rav Nachman said 'Rav Huna says that I and Shmuel are brothers in judging'. He did not intend to praise himself, rather, to explain why he can impose fines by himself. Otherwise, even a Gadol can fine only if the Rabim appointed him or the Tuvei ha'Ir are with him and consent.

Rema: This is the custom everywhere, that Tuvei ha'Ir in their city are like Beis Din ha'Gadol. They can lash, punish and make Hefker according to the custom. Some argue and say that Tuvei ha'Ir can force the Tzibur only to fulfill existing customs or what the entire Tzibur agreed to. They cannot change anything that will cause benefit for some and a loss for others, or make Hefker without everyone's consent. In any case we follow the custom in the city, and all the more so if the city accepted the Tuvei ha'Ir to do everything. The Acharonim write in Teshuvos that one who is Chayav lashes should give 40 gold coins in place of lashes. This is not the law; they ruled for the time. Beis Din can lash or take money as they see fit for Migdar Milsa (a fence against transgression).

SMA (13): The Darchei Moshe connotes that the argument is only about things not necessary for Migdar Milsa. All agree that Tuvei ha'Ir can do what is needed for Migdar Milsa. However, the Mordechai connotes that causing benefit for some and a loss for others is never Migdar Milsa.

Darchei Moshe (2): The Mordechai and Rashba say that the leaders of any Tzibur are like Ge'onim who made many enactments for all of Yisrael - 'Yiftach in his generation is like Shmuel in his generation.'

SMA (11): The Terumas ha'Deshen says that a Beis Din can make Hefker only if it is greater than every other Beis Din in its generation.