Gemara

2a (Mishnah): If witnesses testify that a Kohen is the son of a Gerushah (divorcee) and they were Huzmu, they receive 40 lashes.

2b (Rav Nachman): Edim Zomemim must be a Kenas. The Nidon still has his money, yet they pay.

4a (Mishnah - R. Meir): if Edim Zomemim testified that Reuven is liable to receive 40 lashes, they receive 80 lashes, 40 for "Lo Sa'aneh", and 40 for "Va'Asisem Lo Ka'asher Zomam."

Chachamim say, he is only lashed 40.

4b: Chachamim hold that "Lo Sa'aneh" is the warning for Edim Zomemim. R. Meir holds that it is "Veha'Nish'arim Yishme'u v'Yira'u v'Lo Yosifu" (so he obligates another 40 lashes for Lo Sa'aneh).

5b (Mishnah): When two pairs of witnesses testified about a murder, and did not see each other, if one pair was Huzam, we kill them and the Nidon. The other pair is exempt.

Yerushalmi (Makos 4a): We learn here what we do not learn in all of Sanhedrin. We kill them and the Nidon, and the other pair is exempt.

5b (Mishnah): "Va'Asisem Lo Ka'asher Zomam La'asos l'Achiv" connotes that the Nidon is still alive.

(Beraisa - Beribi): If they did not kill, they are killed, but not if they killed. Ein Onshim Min ha'Din (we do not punish based on a Kal va'Chomer).

(Beraisa) Suggestion: "V'Ish Asher Yikach Es Achoso Bas Aviv Oh Vas Imo" obligates for a paternal or maternal sister. "Ervas Achoso Gilah" obligates for a sister from both parents!

Question: Since one is liable for a half sister, and all the more so he should be liable for a full sister. Why is the verse needed?

Answer: This teaches that Ein Onshim Min ha'Din.

14a: Question: What is R. Yitzchak's source to obligate for a full sister?)

Answer #1: He learns the punishment from the Lav. ("Achoscha Hi" forbids a full sister.)

Answer #2: He learns from the beginning of the verse ("Achoso Bas Aviv Oh Vas Imo." 'Achoso' is extra to teach about a full sister).

(Beraisa - R. Akiva) Question: If one has Bi'ah with his sister, who is also the sister of his father and mother, how many times is he liable?

Answer (Raban Gamliel and R. Yehoshua): We heard only that if one has Bi'ah with five Nidos in one He'elam, he is liable for each woman.

If he is liable for each when they are the same Isur (Nidah), and all the more so for different Arayos (sister, paternal aunt, maternal aunt)!

Rejection: He is liable for each Nidah, for they are different women!

Rishonim

Rambam (Hilchos Edus 20:2): If the Nidon was killed and afterwards the witnesses were Huzmu, we do not rely on a Kal va'Chomer to kill them. It says "Ka'asher Zomam", i.e. they did not yet do it. However, if the Nidon was lashed (and then they were Huzmu), the witnesses are lashed. If the money was transferred, it is returned, and the witnesses pay him.

Rebuttal (Ra'avad): This is wrong.

Kesef Mishneh: What is the Rambam's source to distinguish lashes from Misah? There is no logic to distinguish them. "Like they plotted, but not like they did" should apply also to lashes. It seems that the Ra'avad holds like this. However, R. Yerucham holds like the Rambam. It seems that "like they plotted, but not like they did" applies only to Misah, for their sin is too great to bear. It is improper to execute them to atone for them. Rather, they should get awesome punishments after death. We find that one who gives from his seed to Molech (an idolatry, or a ritual like idolatry) is killed, but not one who gives all his seed (Sanhedrin 64b). The sin of witnesses who caused the Nidon to be lashed is not so great. Also, since "Elokim stands in the congregation of Kel (amidst the judges)", Hash-m would not have allowed a Yisrael to be killed if he were innocent. Therefore, the witnesses are not worthy of death. This does not apply to lashes.

Radvaz: It seems that the Ra'avad asks why we accept Hazamah after the Nidon was killed. We can answer that after Hazamah they are disqualified from testimony, and Beis Din does not kill them, but they punish them like they see fit.

Note: Surely, the Mishnah (Makos 5b) teaches that the other pair is exempt even if it is Huzam! Perhaps one could explain that since it would be exempt, we do not accept Hazamah on it.

Radvaz: Perhaps the Ra'avad asks why we lash Edim Zomemim after the Nidon was lashed. We can answer that "va'Asisem Lo Ka'asher Zomam La'asos l'Achiv" connotes that the Nidon is still alive. Therefore, we do not punish after he was killed, but we punish after he was lashed. This requires investigation.

Mar'eh ha'Panim (Yerushalmi 4a DH Taninan): The other pair is exempt even if it was Huzam. This does not apply to all the laws in Sanhedrin regarding lashes and money, for which we do not say 'not like they did.' This is the Rambam's source. If not, what does 'we learn here what we do not learn in all of Sanhedrin' teach?

Tumim 38:1 (p.85, column 4): A proof for the Rambam is the Mishnah about Edim Zomemim who testified that Reuven is liable to receive 40 lashes. Why do R. Meir and Chachamim argue about the number of lashes? They should argue about Hazamah after the Nidon was lashed; Edim Zomemim are lashed for "Lo Sa'aneh" only if it is not the warning for "Ka'asher Zomam"! Rather, Chachamim agree that he is lashed even in this case.

Note: Seemingly, they argue about the number of lashes, and from this we can derive the law if the Nidon was already lashed! If we only taught the latter, one might have thought that R. Meir obligates lashes for Lo Sa'aneh only when there are no lashes for Ka'asher Zomam, due to "Kedei Rish'aso"! (We initially said that this is Chachamim's reason.)

Me'iri (Makos 3a DH Zeh she'Bi'arnu): We said 'even though the Nidon still has his money, Edim Zomemim pay.' Some learn from this that just like if the Nidon was killed, we do not kill the witnesses, if the Nidon paid, they need not pay, and if he was lashed, they are not lashed. The Ra'avad's Hagahah alludes to this regarding lashes. I disagree, for we expounded so only regarding Misah. Here, the Gemara just means that even if the Nidon did not yet pay, Edim Zomemim pay (this shows that it is a Kenas). The Rambam says so, and the Ra'avad said so in a Teshuvah.

Ramban (Devarim 19:19): If the witnesses were Huzmu after the Nidon was killed, we assume that their testimony was true. If he were innocent, Hash-m would have saved him - "Hash-m Lo Ya'azvenu v'Yado v'Lo Yarshi'enu b'Hishafto."

Tosfos Yom Tov (Makos 1:9 DH veha'Shniyah): This supports the Kesef Mishneh's latter Perush. However, the Ramban did not discuss lashes. We cannot assume that this is the reason and learn from it Halachos (to exempt if the Nidon was already lashed), especially since it is a weak reasoning!

Tosfos (14a DH v'Idach): In the first answer, we said that R. Yitzchak learns the punishment from the Lav. I.e. just like we derive a Lav from a Kal va'Chomer, we derive a punishment from it. This is his source for Onshim Min ha'Din.